Sembrano sintomi del tipo "il Processore s'è brasato"...
Segui il consiglio di Simo. Se non si avvia nemmeno Linux "in LiveCD", significa che hai un danno all'Hardware.

Può darsi. Quindi:

1.Scarica HijackThis da qui: http://software.aiutamici.com/software?ID=11175
2.Segui bene le istruzioni che ci sono nel link che ti ho postato
3.Posta qui il log che rilascia.

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segui bene queste istruzioni:

1.Installa Malwarebytes' (sulla scheda ci sono tutte le istruzioni): http://software.aiutamici.com/software?ID=80346
2.Aggiornalo
3.Esegui la scansione COMPLETA del tuo sistema
4.Se rileva qualcosa NON ELIMINARE NULLA ma posta qui il log che rilascerà

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 20.03.13, on 31/08/2009
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16735)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\SYSTEM32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Programmi\Avira\AntiVir PersonalEdition Classic\sched.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\rundll32.exe
C:\WINDOWS\vVX3000.exe
C:\Program Files\Conexant\Adsl\dslagent.exe
C:\Programmi\Creative\SBLive 24-Bit External\Surround Mixer\CTSysVol.exe
C:\WINDOWS\system32\RunDll32.exe
C:\Programmi\Java\jre6\bin\jusched.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programmi\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\Programmi\Windows Live\Messenger\msnmsgr.exe
C:\Programmi\Messenger\msmsgs.exe
C:\Programmi\Skype\Phone\Skype.exe
C:\Programmi\Creative\MediaSource\RemoteControl\RcMan.exe
C:\Programmi\USRobotics\Wireless USB Manager\USR54G.exe
C:\Programmi\Logitech\Desktop Messenger\8876480\Program\LogitechDesktopMessenger.exe
C:\Programmi\Logitech\SetPoint\SetPoint.exe
C:\Programmi\File comuni\Logishrd\KHAL2\KHALMNPR.EXE
C:\Programmi\Avira\AntiVir PersonalEdition Classic\avguard.exe
C:\WINDOWS\system32\CTsvcCDA.EXE
C:\Programmi\Java\jre6\bin\jqs.exe
C:\Programmi\File comuni\LightScribe\LSSrvc.exe
C:\Programmi\Microsoft LifeCam\MSCamS32.exe
C:\Programmi\Microsoft\Search Enhancement Pack\SeaPort\SeaPort.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\wscntfy.exe
C:\WINDOWS\system32\wbem\wmiapsrv.exe
C:\WINDOWS\System32\svchost.exe
C:\Programmi\Windows Live\Contacts\wlcomm.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Programmi\Avira\AntiVir PersonalEdition Classic\avnotify.exe
C:\Programmi\Mozilla Firefox\firefox.exe
C:\Programmi\Avira\AntiVir PersonalEdition Classic\avgnt.exe
C:\Programmi\Trend Micro\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://g.msn.com/0SEENUS/SAOS01?FORM=TOOLBR
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://g.msn.com/0SEENUS/SAOS01?FORM=TOOLBR
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.it/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://g.msn.com/0SEENUS/SAOS01?FORM=TOOLBR
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyServer = 192.168.0.1:808
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = 127.0.0.1
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Collegamenti
R3 - URLSearchHook: SweetIM ToolbarURLSearchHook Class - {EEE6C35D-6118-11DC-9C72-001320C79847} - C:\Programmi\SweetIM\Toolbars\Internet Explorer\mgHelper.dll
O2 - BHO: Supporto di collegamento per Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Programmi\File comuni\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: E-Zsoft VideoDownloaderToolBar - {4322A444-92F8-4C3E-BD4C-013BA51E2871} - C:\Programmi\VersalSoft\InternetDownload\VDTB.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O2 - BHO: Search Helper - {6EBF7485-159F-4bff-A14F-B9E3AAC4465B} - C:\Programmi\Microsoft\Search Enhancement Pack\Search Helper\SearchHelper.dll
O2 - BHO: UrlHelper Class - {74322BF9-DF26-493f-B0DA-6D2FC5E6429E} - C:\Programmi\BearShare Applications\BearShare MediaBar\BearShareIEHelper.dll
O2 - BHO: Guida per l'accesso a Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Programmi\File comuni\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Programmi\Java\jre6\bin\jp2ssv.dll
O2 - BHO: Windows Live Toolbar Helper - {E15A8DC0-8516-42A1-81EA-DC94EC1ACF10} - C:\Programmi\Windows Live\Toolbar\wltcore.dll
O2 - BHO: JQSIEStartDetectorImpl - {E7E6F031-17CE-4C07-BC86-EABFE594F69C} - C:\Programmi\Java\jre6\lib\deploy\jqs\ie\jqs_plugin.dll
O2 - BHO: SWEETIE - {EEE6C35C-6118-11DC-9C72-001320C79847} - C:\Programmi\SweetIM\Toolbars\Internet Explorer\mgToolbarIE.dll
O3 - Toolbar: E-Zsoft VideoDownloaderToolBar - {4322A444-92F8-4C3E-BD4C-013BA51E2871} - C:\Programmi\VersalSoft\InternetDownload\VDTB.dll
O3 - Toolbar: SweetIM Toolbar for Internet Explorer - {EEE6C35B-6118-11DC-9C72-001320C79847} - C:\Programmi\SweetIM\Toolbars\Internet Explorer\mgToolbarIE.dll
O3 - Toolbar: BearShare MediaBar - {D3DEE18F-DB64-4BEB-9FF1-E1F0A5033E4A} - C:\Programmi\BearShare Applications\BearShare MediaBar\BearShareMediaBar.dll
O3 - Toolbar: &Windows Live Toolbar - {21FA44EF-376D-4D53-9B0F-8A89D3229068} - C:\Programmi\Windows Live\Toolbar\wltcore.dll
O4 - HKLM\..\Run: [ATIModeChange] Ati2mdxx.exe
O4 - HKLM\..\Run: [BluetoothAuthenticationAgent] rundll32.exe bthprops.cpl,,BluetoothAuthenticationAgent
O4 - HKLM\..\Run: [PinnacleDriverCheck] C:\WINDOWS\system32\PSDrvCheck.exe -CheckReg
O4 - HKLM\..\Run: [avgnt] "C:\Programmi\Avira\AntiVir PersonalEdition Classic\avgnt.exe" /min
O4 - HKLM\..\Run: [LifeCam] "C:\Programmi\Microsoft LifeCam\LifeExp.exe"
O4 - HKLM\..\Run: [VX3000] C:\WINDOWS\vVX3000.exe
O4 - HKLM\..\Run: [mmtask] c:\Program Files\MusicMatch\MusicMatch Jukebox\mmtask.exe
O4 - HKLM\..\Run: [DSLSTATEXE] C:\Program Files\Conexant\Adsl\dslstat.exe icon
O4 - HKLM\..\Run: [DSLAGENTEXE] C:\Program Files\Conexant\Adsl\dslagent.exe
O4 - HKLM\..\Run: [CTSysVol] C:\Programmi\Creative\SBLive 24-Bit External\Surround Mixer\CTSysVol.exe /r
O4 - HKLM\..\Run: [SbUsb AudCtrl] RunDll32 sbusbdll.dll,RCMonitor
O4 - HKLM\..\Run: [UpdReg] C:\WINDOWS\UpdReg.EXE
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programmi\Java\jre6\bin\jusched.exe"
O4 - HKLM\..\Run: [KernelFaultCheck] %systemroot%\system32\dumprep 0 -k
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [Philips Intelligent Agent] NOT_IN_USE_DUMMY_PATH
O4 - HKCU\..\Run: [SUPERAntiSpyware] C:\Programmi\SUPERAntiSpyware\SUPERAntiSpyware.exe
O4 - HKCU\..\Run: [msnmsgr] "C:\Programmi\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKCU\..\Run: [MSMSGS] "C:\Programmi\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [AdobeUpdater] C:\Programmi\File comuni\Adobe\Updater5\AdobeUpdater.exe
O4 - HKCU\..\Run: [Skype] "C:\Programmi\Skype\Phone\Skype.exe" /nosplash /minimized
O4 - HKCU\..\Run: [RemoteCenter] C:\Programmi\Creative\MediaSource\RemoteControl\RcMan.exe
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVIZIO LOCALE')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVIZIO DI RETE')
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O4 - Global Startup: USRobotics Wireless USB Adapter.lnk = C:\Programmi\USRobotics\Wireless USB Manager\USR54G.exe
O4 - Global Startup: Logitech Desktop Messenger.lnk = C:\Programmi\Logitech\Desktop Messenger\8876480\Program\LogitechDesktopMessenger.exe
O4 - Global Startup: Logitech SetPoint.lnk = C:\Programmi\Logitech\SetPoint\SetPoint.exe
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~4\Office10\EXCEL.EXE/3000
O9 - Extra button: Inserisci blog - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Programmi\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra 'Tools' menuitem: Inserisci &blog in Windows Live Writer - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Programmi\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programmi\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programmi\Messenger\msmsgs.exe
O18 - Protocol: bwfile-8876480 - {9462A756-7B47-47BC-8C80-C34B9B80B32B} - C:\Programmi\Logitech\Desktop Messenger\8876480\Program\GAPlugProtocol-8876480.dll
O20 - Winlogon Notify: !SASWinLogon - C:\Programmi\SUPERAntiSpyware\SASWINLO.dll
O23 - Service: Avira AntiVir Personal - Free Antivirus Scheduler (AntiVirScheduler) - Avira GmbH - C:\Programmi\Avira\AntiVir PersonalEdition Classic\sched.exe
O23 - Service: Avira AntiVir Personal - Free Antivirus Guard (AntiVirService) - Avira GmbH - C:\Programmi\Avira\AntiVir PersonalEdition Classic\avguard.exe
O23 - Service: Creative Service for CDROM Access - Creative Technology Ltd - C:\WINDOWS\system32\CTsvcCDA.EXE
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Programmi\Java\jre6\bin\jqs.exe
O23 - Service: Logitech Bluetooth Service (LBTServ) - Logitech, Inc. - C:\Programmi\File comuni\Logishrd\Bluetooth\LBTServ.exe
O23 - Service: LightScribeService Direct Disc Labeling Service (LightScribeService) - Hewlett-Packard Company - C:\Programmi\File comuni\LightScribe\LSSrvc.exe
O23 - Service: MySQL - Unknown owner - C:\WM\MySQL-4.1.12\bin\mysqld-nt.exe
O23 - Service: NBService - Nero AG - C:\Programmi\Nero\Nero 7\Nero BackItUp\NBService.exe
O23 - Service: NMIndexingService - Nero AG - C:\Programmi\File comuni\Ahead\Lib\NMIndexingService.exe
O23 - Service: ServiceLayer - Nokia. - C:\Programmi\File comuni\PCSuite\Services\ServiceLayer.exe
O23 - Service: WMServerTools - Apache - Apache Software Foundation - C:\WM\Apache-2.0.54\bin\Apache.exe
O23 - Service: WMServerTools - MySQL - Unknown owner - C:\WM\MySQL-4.1.12\bin\mysqld-nt.exe

--
End of file - 10318 bytes

Giusta osservazione monsee.

Un secondo solo, controllo il log.

Ciao

ora non riesce a partire
se vado in modalità provvisoria si blocca explorer e devo riavviarlo
se poi riesce a partire normale mi da errore per xp contraffatto
oppure tenta di avviarsi e poi rimane bloccato a schermo nero
che devo fare?
grazie

Ma il tuo Xp è originale?

non riesce a finire la scansione che si riavvia

quella rapita non mi trova nulla
ma ora non si riavvia in nessun modo