Ciao Alfonso,
ho eseguito quanto consigliato da te.
In modalità provvisoria ho eseguito Avast,Ad-Aware,
Spybot ma non hanno trovato niente.
Ciao

Non ho evidenza di qualche problema al PC.
Ti invio quanto chiesto.
Logfile of HijackThis v1.98.2
Scan saved at 18.23.16, on 11/12/04
Platform: Windows 98 SE (Win9x 4.10.2222A)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

Running processes:
C:\WINDOWS\SYSTEM\KERNEL32.DLL
C:\WINDOWS\SYSTEM\MSGSRV32.EXE
C:\WINDOWS\SYSTEM\MPREXE.EXE
C:\WINDOWS\SYSTEM\MSTASK.EXE
C:\PROGRAMMI\ALWIL SOFTWARE\AVAST4\ASHSERV.EXE
C:\PROGRAMMI\EXECUTIVE SOFTWARE\DISKEEPERLITE\DKSERVICE.EXE
C:\WINDOWS\SYSTEM\mmtask.tsk
C:\PROGRAMMI\SYGATE\SPF\SMC.EXE
C:\WINDOWS\EXPLORER.EXE
C:\WINDOWS\TASKMON.EXE
C:\WINDOWS\SYSTEM\SYSTRAY.EXE
C:\PROGRAMMI\FILE COMUNI\ADAPTEC SHARED\CREATECD\CREATECD50.EXE
C:\PROGRAMMI\ADAPTEC\EASY CD CREATOR 5\DIRECTCD\DIRECTCD.EXE
C:\WINDOWS\SYSTEM\STIMON.EXE
C:\WINDOWS\SYSTEM\RPCSS.EXE
C:\WINDOWS\RUNDLL32.EXE
C:\PROGRAMMI\CREATIVE\PC-CAM CENTER\CAMTRAY.EXE
C:\WINDOWS\LOADQM.EXE
C:\WINDOWS\SYSTEM\DDHELP.EXE
C:\PROGRAMMI\ALWIL SOFTWARE\AVAST4\ASHMAISV.EXE
C:\PROGRAMMI\FILE COMUNI\REAL\UPDATE_OB\REALSCHED.EXE
C:\WINDOWS\SYSTEM\QTTASK.EXE
C:\PROGRAMMI\MSN MESSENGER\MSNMSGR.EXE
C:\WINDOWS\SYSTEM\CTFMON.EXE
C:\PROGRAMMI\ADOBE\ACROBAT 5.0\DISTILLR\ACROTRAY.EXE
C:\WINDOWS\SYSTEM\RNAAPP.EXE
C:\WINDOWS\SYSTEM\TAPISRV.EXE
C:\WINDOWS\SYSTEM\PSTORES.EXE
C:\PROGRAMMI\INTERNET EXPLORER\IEXPLORE.EXE
D:\TEMP\HIJACKTHIS.EXE

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://crackspider.net/ie/sbar.php
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,SearchAssistant = http://crackspider.net/ie/assist.php
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\PROGRAMMI\ADOBE\ACROBAT 5.0\ACROBAT\ACTIVEX\ACROIEHELPER.OCX
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\SYSTEM\MSDXM.OCX
O4 - HKLM\..\Run: [ScanRegistry] C:\WINDOWS\scanregw.exe /autorun
O4 - HKLM\..\Run: [TaskMonitor] C:\WINDOWS\taskmon.exe
O4 - HKLM\..\Run: [SystemTray] SysTray.Exe
O4 - HKLM\..\Run: [CreateCD50] "C:\Programmi\File comuni\Adaptec Shared\CreateCD\CreateCD50.exe" -r
O4 - HKLM\..\Run: [AdaptecDirectCD] "C:\Programmi\Adaptec\Easy CD Creator 5\DirectCD\DirectCD.exe"
O4 - HKLM\..\Run: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\Run: [StillImageMonitor] C:\WINDOWS\SYSTEM\STIMON.EXE
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE NvQTwk,NvCplDaemon initialize
O4 - HKLM\..\Run: [CriticalUpdate] C:\WINDOWS\SYSTEM\wucrtupd.exe -startup
O4 - HKLM\..\Run: [AdslTaskBar] rundll32.exe stmctrl.dll,TaskBar
O4 - HKLM\..\Run: [Creative WebCam Tray] C:\Programmi\Creative\PC-CAM Center\CAMTRAY.EXE
O4 - HKLM\..\Run: [LoadQM] loadqm.exe
O4 - HKLM\..\Run: [ashMaiSv] C:\PROGRA~1\ALWILS~1\AVAST4\ashmaisv.exe
O4 - HKLM\..\Run: [TkBellExe] "C:\Programmi\File comuni\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [SmcService] C:\PROGRA~1\SYGATE\SPF\SMC.EXE -startgui
O4 - HKLM\..\Run: [Tweak UI] RUNDLL32.EXE TWEAKUI.CPL,TweakMeUp
O4 - HKLM\..\Run: [QuickTime Task] "C:\WINDOWS\SYSTEM\QTTASK.EXE" -atboottime
O4 - HKLM\..\RunServices: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\RunServices: [SchedulingAgent] mstask.exe
O4 - HKLM\..\RunServices: [avast!] C:\Programmi\Alwil Software\Avast4\ashServ.exe
O4 - HKLM\..\RunServices: [DkService] C:\Programmi\Executive Software\DiskeeperLite\DkService.exe
O4 - HKLM\..\RunServices: [SmcService] C:\PROGRAMMI\SYGATE\SPF\SMC.EXE
O4 - HKCU\..\Run: [msnmsgr] "C:\PROGRAMMI\MSN MESSENGER\MSNMSGR.EXE" /background
O4 - HKCU\..\Run: [ctfmon.exe] ctfmon.exe
O4 - Startup: Microsoft Office.lnk = C:\Programmi\Microsoft Office\Office10\OSA.EXE
O4 - Startup: Acrobat Assistant.lnk = C:\Programmi\Adobe\Acrobat 5.0\Distillr\AcroTray.exe
O8 - Extra context menu item: E&sporta in Microsoft Excel - res://C:\PROGRA~1\MICROS~1\OFFICE10\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\WINDOWS\SYSTEM\MSJAVA.DLL
O9 - Extra 'Tools' menuitem: Sun Java Console - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\WINDOWS\SYSTEM\MSJAVA.DLL
O12 - Plugin for .spop: C:\PROGRA~1\INTERN~1\Plugins\NPDocBox.dll
O17 - HKLM\System\CCS\Services\VxD\MSTCP: Domain = tin.it
O17 - HKLM\System\CCS\Services\VxD\MSTCP: NameServer = 62.211.69.150,212.48.4.15

Ciao Alfonso,
Ho eseguito in modalità provvisoria,dopo aver cancellato le due voci R1, quanto segnalato da te.
Risultato:sia AD-AWARE sia SPYBOT e AVAST non hanno segnalato questo Worm.
Inoltre sono andato sul Forum di A2 e leggendo le varie informazioni sembra che questo Worm legato a Taskmon.exe risulti un falso positivo.Ti segnalo dove ho letto questa informazione.
http://forum.emsisoft.com/viewforum.php?f=2