Impossible d'installer un anti-virus

Bonjour,
Mon ordi est infecté je pense, il me ferme internet ("ne répond pas") ou d'autres logiciel et impossible de télécharger un antivirus, ça bug lors de l'installation. toute aide serait la bienvenue merci mille fois.!! g fait un scan avec HiJackthis dont voici le rapport (g lu sur des forum que ça pouvait être utile !)

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 00:42:01, on 26/03/2012
Platform: Unknown Windows (WinNT 6.01.3504)
MSIE: Internet Explorer v9.00 (9.00.8112.16421)
Boot mode: Normal

Running processes:
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Windows\system32\taskhost.exe
C:\Program Files\Common Files\Java\Java Update\jusched.exe
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup\Little transparency.exe
C:\Program Files\RocketDock\RocketDock.exe
C:\Windows\system32\wuauclt.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Mozilla Firefox\plugin-container.exe
C:\Windows\system32\taskhost.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe
C:\Windows\system32\SearchFilterHost.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.igoogle.fr/
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
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: Search Class - {08C06D61-F1F3-4799-86F8-BE1A89362C85} - C:\Program Files\OrangeHSS\SearchURLHook\SearchPageURL.dll (file missing)
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - C:\Program Files\Google\Google Toolbar\GoogleToolbar_32.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O3 - Toolbar: Google Toolbar - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - C:\Program Files\Google\Google Toolbar\GoogleToolbar_32.dll
O4 - HKLM\..\Run: [Adobe ARM] "C:\Program Files\Common Files\Adobe\ARM\1.0\AdobeARM.exe"
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Common Files\Java\Java Update\jusched.exe"
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User '?')
O4 - HKUS\S-1-5-19\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User '?')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User '?')
O4 - HKUS\S-1-5-20\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User '?')
O4 - HKUS\S-1-5-18\..\Run: [Welcome Center] C:\Windows\system32\rundll32.exe C:\Windows\system32\OobeFldr.dll,ShowWelcomeCenter LaunchedBy_StartMenuShortcut (User '?')
O4 - HKUS\.DEFAULT\..\Run: [Welcome Center] C:\Windows\system32\rundll32.exe C:\Windows\system32\OobeFldr.dll,ShowWelcomeCenter LaunchedBy_StartMenuShortcut (User 'Default user')
O4 - Global Startup: Little transparency.exe
O4 - Global Startup: RocketDock.lnk = C:\Program Files\RocketDock\RocketDock.exe
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~3\OFFICE11\EXCEL.EXE/3000
O8 - Extra context menu item: Google Sidewiki... - res://C:\Program Files\Google\Google Toolbar\Component\GoogleToolbarDynamic_mui_en_6CE5017F567343CA.dll/cmsidewiki.html
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~3\OFFICE11\REFIEBAR.DLL
O11 - Options group: [ACCELERATED_GRAPHICS] Accelerated graphics
O13 - Gopher Prefix:
O15 - Trusted Zone: http://*.mappy.com
O15 - Trusted Zone: http://*.orange.fr
O15 - Trusted Zone: http://rw.search.ke.voila.fr
O15 - Trusted Zone: http://orange.weborama.fr
O23 - Service: Adobe Acrobat Update Service (AdobeARMservice) - Adobe Systems Incorporated - C:\Program Files\Common Files\Adobe\ARM\1.0\armsvc.exe
O23 - Service: Service Google Update (gupdate) (gupdate) - Google Inc. - C:\Program Files\Google\Update\GoogleUpdate.exe
O23 - Service: Service Google Update (gupdatem) (gupdatem) - Google Inc. - C:\Program Files\Google\Update\GoogleUpdate.exe
O23 - Service: Google Software Updater (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe