Mon PC s'arrete et redemarre tout seul

Bonjour,
Mon pc s'arrete et redemarre tout seul quand je suis connecté a internet.(Ne le fait pas tout le temps mais de temps en temps).
Merci pour votre aide.
Voici le rapport hijacthis :
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 12:29:47, on 04/11/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16544)
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\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Apps\ActivBoard\nhksrv.exe
C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Program Files\Wireless 802.11g Monitor\WLService.exe
C:\Program Files\Wireless 802.11g Monitor\WLanCfgG.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Communicator\xcommsvr.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Update Service\livesrv.exe
C:\PROGRA~1\MOUSEW~1\SYSTEM\EM_EXEC.EXE
C:\Program Files\QuickTime\qttask.exe
C:\Program Files\TechCity Solutions\AliceSAV\AliceAgent.exe
C:\Program Files\Softwin\BitDefender10\bdmcon.exe
C:\Program Files\Softwin\BitDefender10\bdagent.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Java\jre1.5.0_10\bin\jusched.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
C:\Program Files\Google\Google Updater\GoogleUpdater.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\PROGRA~1\IZArc\IZArc.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Scan Server\bdss.exe
C:\Program Files\Softwin\BitDefender10\vsserv.exe
C:\DOCUME~1\Mathilde\LOCALS~1\Temp\ARC2A1\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://portail.free.fr/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Microsoft Internet Explorer fourni par Planetis
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - (no file)
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\apps\Adobe\Acrobat 5.0\Reader\ActiveX\AcroIEHelper.ocx
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.1.615.5858\swg.dll
O3 - Toolbar: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [EM_EXEC] C:\PROGRA~1\MOUSEW~1\SYSTEM\EM_EXEC.EXE
O4 - HKLM\..\Run: [Synchronization Manager] %SystemRoot%\system32\mobsync.exe /logon
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [AliceSAV] C:\Program Files\TechCity Solutions\AliceSAV\AliceAgent.exe
O4 - HKLM\..\Run: [BDMCon] "C:\Program Files\Softwin\BitDefender10\bdmcon.exe" /reg
O4 - HKLM\..\Run: [BDAgent] "C:\Program Files\Softwin\BitDefender10\bdagent.exe"
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.5.0_10\bin\jusched.exe"
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [KernelFaultCheck] %systemroot%\system32\dumprep 0 -k
O4 - HKCU\..\Run: [MoneyAgent] "C:\Program Files\Microsoft Money\System\Money Express.exe"
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - Global Startup: DSLMON.lnk = C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O4 - Global Startup: Outil de mise à jour Google.lnk = C:\Program Files\Google\Google Updater\GoogleUpdater.exe
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O9 - Extra button: (no name) - {85d1f590-48f4-11d9-9669-0800200c9a66} - C:\WINDOWS\bdoscandel.exe
O9 - Extra 'Tools' menuitem: Uninstall BitDefender Online Scanner v8 - {85d1f590-48f4-11d9-9669-0800200c9a66} - C:\WINDOWS\bdoscandel.exe
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
O16 - DPF: Interface Chat Voila - http://chat4.x-echo.com/version8/Applet/vchatsign.cab
O16 - DPF: teleir_cert - https://static.ir.dgi.minefi.gouv.fr/secure/connexion/archives/teleir_cert.cab
O16 - DPF: {00B71CFB-6864-4346-A978-C0A14556272C} (Checkers Class) - http://messenger.zone.msn.com/binary/msgrchkr.cab31267.cab
O16 - DPF: {0246ECA8-996F-11D1-BE2F-00A0C9037DFE} (TDServer Control) - https://actu.orange.fr/
O16 - DPF: {17492023-C23A-453E-A040-C7C580BBF700} (Windows Genuine Advantage Validation Tool) - http://download.microsoft.com/download/E/5/6/E5611B10-0D6D-4117-8430-A67417AA88CD/LegitCheckControl.cab
O16 - DPF: {2BC66F54-93A8-11D3-BEB6-00105AA9B6AE} (Symantec AntiVirus scanner) - http://security.symantec.com/sscv6/SharedContent/vc/bin/AvSniff.cab
O16 - DPF: {4E888414-DB8F-11D1-9CD9-00C04F98436A} (Microsoft.WinRep) - https://webresponse.one.microsoft.com/oas/ActiveX/winrep.cab
O16 - DPF: {5D86DDB5-BDF9-441B-9E9E-D4730F4EE499} (BDSCANONLINE Control) - http://www.bitdefender.fr/scan8/oscan8.cab
O16 - DPF: {5ED80217-570B-4DA9-BF44-BE107C0EC166} (Windows Live Safety Center Base Module) - http://cdn.scan.onecare.live.com/resource/download/scanner/wlscbase9602.cab
O16 - DPF: {8167C273-DF59-4416-B647-C8BB2C7EE83E} (WebSDev Control) - http://tw.msi.com.tw/autobios/LOnline/install.cab
O16 - DPF: {8E0D4DE5-3180-4024-A327-4DFAD1796A8D} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsClient.cab31267.cab
O16 - DPF: {8F48147B-78D9-40F9-ACC0-BDDE59B246F4} (AccountHelper Class) - http://abonnement.aliceadsl.fr/configurateur/AccountHelper.cab
O16 - DPF: {E862C832-3A5F-4CEB-BFAA-167B22010A71} (InfosFinder2.InfosFinder) - http://support.packardbell.com/files/activex/InfosFinder2.CAB
O23 - Service: BitDefender Scan Server (bdss) - Unknown owner - C:\Program Files\Fichiers communs\Softwin\BitDefender Scan Server\bdss.exe
O23 - Service: Boonty Games - BOONTY - C:\Program Files\Fichiers communs\BOONTY Shared\Service\Boonty.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: BitDefender Desktop Update Service (LIVESRV) - SOFTWIN S.R.L. - C:\Program Files\Fichiers communs\Softwin\BitDefender Update Service\livesrv.exe
O23 - Service: Netropa NHK Server (nhksrv) - Unknown owner - C:\Apps\ActivBoard\nhksrv.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: R54G Wireless Service - Unknown owner - C:\Program Files\Wireless 802.11g Monitor\WLService.exe
O23 - Service: BitDefender Virus Shield (VSSERV) - SOFTWIN S.R.L. - C:\Program Files\Softwin\BitDefender10\vsserv.exe
O23 - Service: BitDefender Communicator (XCOMM) - Softwin - C:\Program Files\Fichiers communs\Softwin\BitDefender Communicator\xcommsvr.exe