Logfile of Trend Micro HijackThis v2.0.5
Scan saved at 17:43:42, on 29/05/2016
Platform: Windows 7 SP1 (WinNT 6.00.3505)
MSIE: Internet Explorer v11.0 (11.00.9600.18315)

FIREFOX: 46.0.1 (x86 it)
Boot mode: Normal

Running processes:
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Program Files\Panda Security\Panda Security Protection\PSUAMain.exe
C:\Program Files\System Explorer\SystemExplorer.exe
C:\Program Files\Windows Sidebar\sidebar.exe
C:\Windows\system32\DllHost.exe
C:\Program Files\PDF24\pdf24.exe
C:\Program Files\Common Files\Java\Java Update\jusched.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Windows\system32\SearchFilterHost.exe
C:\Users\Sergio\Desktop\HijackThisPortable\HijackThisPortable.exe
C:\Users\Sergio\Desktop\HijackThisPortable\App\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/p/?LinkId=619797&pc=UE07&ocid=UE07DHP
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 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.8.0_91\bin\ssv.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre1.8.0_91\bin\jp2ssv.dll
O4 - HKLM\..\Run: [PSUAMain] "C:\Program Files\Panda Security\Panda Security Protection\PSUAMain.exe" /LaunchSysTray
O4 - HKLM\..\Run: [SunJavaUpdateSched] C:\Program Files\jv16 PowerTools X\StartupOptimizer.exe "C:\Program Files\Common Files\Java\Java Update\jusched.exe"
O4 - HKLM\..\Run: [SystemExplorerAutoStart] "C:\Program Files\System Explorer\SystemExplorer.exe" /TRAY
O4 - HKLM\..\Run: [PDFPrint] C:\Program Files\jv16 PowerTools X\StartupOptimizer.exe "C:\Program Files\PDF24\pdf24.exe"
O4 - HKCU\..\Run: [Sidebar] C:\Program Files\Windows Sidebar\sidebar.exe /autoRun
O4 - HKCU\..\Run: [eM Client] "C:\Program Files\eM Client\MailClient.exe" /startup
O4 - HKUS\S-1-5-18\..\RunOnce: [SPReview] "C:\Windows\System32\SPReview\SPReview.exe" /sp:1 /errorfwlink:"http://go.microsoft.com/fwlink/?LinkID=122915" /build:7601 (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\RunOnce: [SPReview] "C:\Windows\System32\SPReview\SPReview.exe" /sp:1 /errorfwlink:"http://go.microsoft.com/fwlink/?LinkID=122915" /build:7601 (User 'Default user')
O9 - Extra button: Skype Click to Call settings - {898EA8C8-E7FF-479B-8935-AEC46303B9E5} - C:\Program Files\Skype\Toolbars\Internet Explorer\SkypeIEPlugin.dll
O11 - Options group: [ACCELERATED_GRAPHICS] Accelerated graphics
O18 - Protocol: skypec2c - {91774881-D725-4E58-B298-07617B9B86A8} - C:\Program Files\Skype\Toolbars\Internet Explorer\SkypeIEPlugin.dll
O23 - Service: Adobe Flash Player Update Service (AdobeFlashPlayerUpdateSvc) - Adobe Systems Incorporated - C:\Windows\system32\Macromed\Flash\FlashPlayerUpdateService.exe
O23 - Service: Freemake Improver - Freemake - C:\ProgramData\Freemake\FreemakeUtilsService\FreemakeUtilsService.exe
O23 - Service: Mozilla Maintenance Service (MozillaMaintenance) - Mozilla Foundation - C:\Program Files\Mozilla Maintenance Service\maintenanceservice.exe
O23 - Service: Panda Protection Service (NanoServiceMain) - Panda Security, S.L. - C:\Program Files\Panda Security\Panda Security Protection\PSANHost.exe
O23 - Service: Panda Devices Agent (PandaAgent) - Panda Security, S.L. - C:\Program Files\Panda Security\Panda Devices Agent\AgentSvc.exe
O23 - Service: panda_url_filtering Service (panda_url_filtering) - Visicom Media Inc. - C:\ProgramData\Panda Security URL Filtering\Panda_URL_Filteringb.exe
O23 - Service: Panda Product Service (PSUAService) - Panda Security, S.L. - C:\Program Files\Panda Security\Panda Security Protection\PSUAService.exe
O23 - Service: Skype Updater (SkypeUpdate) - Skype Technologies - C:\Program Files\Skype\Updater\Updater.exe
O23 - Service: System Explorer Service (SystemExplorerHelpService) - Mister Group - C:\Program Files\System Explorer\service\SystemExplorerService.exe
O23 - Service: TeamViewer 11 (TeamViewer) - TeamViewer GmbH - C:\Program Files\TeamViewer\TeamViewer_Service.exe

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End of file - 4636 bytes

Per postare un log di HJT che problemi ha il pc ? dal log non si notano irregolarità.

Non so a cosa ti serve questa applicazione, io non la conosco, qui trovi delle soluzioni:
https://translate.google.it/translate?hl=it&sl=en&u=http://api.256file.com/avformat-lav-56.dll/en-download-44785.html&prev=search
Se non risolvi prova a rimuoverla fai una pulizia con Ccleaner e poi la riscarichi sempre dal link che ti ho messo.
Prova a fare una scansione con Malwarebytes e con ADWcleaner che servono sempre. Ciao