Bonjour,
Après lecture des derniers messages concernant Lsass.exe, je ne retrouve pas mon problème.
J'ai le programme Lsass.exe qui me prends 50 à 60 % de temps CPU (gestionnaire de tâches).
j'ai un Duron 1.2 Ghz avec 256 mo de mem avec XP familiale.
J'ai essayé les principaux anti-virus qui m'ont trouvé quelques virus et ad-aware qui m'ont fait le ménage mais lsass.exe tourne toujours pour occuper le CPU à 100 %.

Ne sachant pas analyser le compte rendu de Hijacthis, le voici.
Si une bonne âme peut me donner quelques indications ...
( je fais tourner en ce moment avast).

Logfile of HijackThis v1.97.7
Scan saved at 19:44:29, on 02/06/2004
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Unable to get Internet Explorer version!

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:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\Program Files\Fichiers communs\Microsoft Shared\VS7Debug\mdm.exe
C:\WINDOWS\system32\slserv.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\System32\MsPMSPSv.exe
C:\WINDOWS\Explorer.EXE
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashmaisv.exe
C:\WINDOWS\System32\taskmgr.exe
C:\Program Files\Alwil Software\Avast4\ashSimpl.exe
C:\PROGRA~1\MICROS~2\Office10\OUTLOOK.EXE
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\Documents and Settings\DEWAILLY\Mes documents\a_load\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://g.msn.fr/0SEFRFR/SAOS02
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://home.free.fr/
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
F2 - REG:system.ini: UserInit=C:\WINDOWS\System32\Userinit.exe
O2 - BHO: (no name) - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 6.0\Reader\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\MSDXM.OCX
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [ashMaiSv] C:\PROGRA~1\ALWILS~1\Avast4\ashmaisv.exe
O4 - HKLM\..\Run: [MSConfig] C:\WINDOWS\PCHealth\HelpCtr\Binaries\MSConfig.exe /auto
O8 - Extra context menu item: &Google Search - res://c:\program files\google\GoogleToolbar1.dll/cmsearch.html
O8 - Extra context menu item: Backward &Links - res://c:\program files\google\GoogleToolbar1.dll/cmbacklinks.html
O8 - Extra context menu item: Cac&hed Snapshot of Page - res://c:\program files\google\GoogleToolbar1.dll/cmcache.html
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O8 - Extra context menu item: Si&milar Pages - res://c:\program files\google\GoogleToolbar1.dll/cmsimilar.html
O9 - Extra button: Créer un Favori de l'appareil mobile (HKLM)
O9 - Extra 'Tools' menuitem: Créer un Favori de l'appareil mobile... (HKLM)
O9 - Extra button: Messenger (HKLM)
O9 - Extra 'Tools' menuitem: Messenger (HKLM)
O14 - IERESET.INF: START_PAGE_URL=http://home.free.fr/
O16 - DPF: ppctlcab - http://www.pestscan.com/scanner/ppctlcab.cab
O16 - DPF: teleir_cert - https://static.ir.dgi.minefi.gouv.fr/secure/connexion/archives/ie4n4/teleir_cert.cab
O16 - DPF: {00B71CFB-6864-4346-A978-C0A14556272C} (Checkers Class) - http://messenger.zone.msn.com/binary/msgrchkr.cab
O16 - DPF: {02BCC737-B171-4746-94C9-0D8A0B2C0089} (Microsoft Office Template and Media Control) - http://office.microsoft.com/templates/ieawsdc.cab
O16 - DPF: {02BF25D5-8C17-4B23-BC80-D3488ABDDC6B} (QuickTime Object) - http://www.apple.com/qtactivex/qtplugin.cab
O16 - DPF: {166B1BCA-3F9C-11CF-8075-444553540000} (Shockwave ActiveX Control) - http://download.macromedia.com/pub/shockwave/cabs/director/sw.cab
O16 - DPF: {2BC66F54-93A8-11D3-BEB6-00105AA9B6AE} (Symantec AntiVirus scanner) - http://security.symantec.com/sscv6/SharedContent/vc/bin/AvSniff.cab
O16 - DPF: {2FC9A21E-2069-4E47-8235-36318989DB13} (PPSDKActiveXScanner.MainScreen) - http://www.pestscan.com/scanner/axscanner.cab
O16 - DPF: {3E68E405-C6DE-49FF-83AE-41EE9F4C36CE} (Office Update Installation Engine) - http://office.microsoft.com/officeupdate/content/opuc.cab
O16 - DPF: {40576C8E-093B-11D6-A73D-004005A6F551} (HttploadDlg Class) - http://download.oreka.com/httpload_cab/020220/httpload.cab
O16 - DPF: {41F17733-B041-4099-A042-B518BB6A408C} - http://a1540.g.akamai.net/7/1540/52/20021126/qtinstall.info.apple.com/dribnif/fr/win/QuickTimeInstaller.exe
O16 - DPF: {597C45C2-2D39-11D5-8D53-0050048383FE} (OPUCatalog Class) - http://office.microsoft.com/productupdates/content/opuc.cab
O16 - DPF: {644E432F-49D3-41A1-8DD5-E099162EEEC5} (Symantec RuFSI Utility Class) - http://security.symantec.com/sscv6/SharedContent/common/bin/cabsa.cab
O16 - DPF: {6F6E3A5E-4A75-45F0-BDDE-21B6C4496E2B} (LAInstaller Class) - http://www.cantoche.com/download/LAinstall.cab
O16 - DPF: {74D05D43-3236-11D4-BDCD-00C04F9A3B61} (HouseCall Control) - http://a840.g.akamai.net/7/840/537/2004033001/housecall.antivirus.com/housecall/xscan53.cab
O16 - DPF: {7B297BFD-85E4-4092-B2AF-16A91B2EA103} (WScanCtl Class) - http://www3.ca.com/securityadvisor/virusinfo/webscan.cab
O16 - DPF: {80DD2229-B8E4-4C77-B72F-F22972D723EA} - http://www.bitdefender.com/scan/Msie/bitdefender.cab
O16 - DPF: {814EA0DA-E0D9-4AA4-833C-A1A6D38E79E9} (DASWebDownload Class) - http://das.microsoft.com/activate/cab/x86/i486/NTANSI/retail/DASAct.cab
O16 - DPF: {8E0D4DE5-3180-4024-A327-4DFAD1796A8D} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsClient.cab
O16 - DPF: {917623D1-D8E5-11D2-BE8B-00104B06BDE3} (CamImage Class) - http://217.167.21.128/activex/AxisCamControl.ocx
O16 - DPF: {9A9307A0-7DA4-4DAF-B042-5009F29E09E1} (ActiveScan Installer Class) - http://www.pandasoftware.com/activescan/as5/asinst.cab
O16 - DPF: {9F1C11AA-197B-4942-BA54-47A8489BB47F} (Update Class) - http://v4.windowsupdate.microsoft.com/CAB/x86/unicode/iuctl.CAB?37582.2942824074
O16 - DPF: {A3009861-330C-4E10-822B-39D16EC8829D} (CRAVOnline Object) - http://www.ravantivirus.com/scan/ravonline.cab
O16 - DPF: {C3DFA998-A486-11D4-AA25-00C04F72DAEB} (MSN Photo Upload Tool) - http://sc.communities.msn.com/controls/PhotoUC/MsnPUpld.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-445535400000} - http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab
O16 - DPF: {F58E1CEF-A068-4C15-BA5E-587CAF3EE8C6} (MSN Chat Control 4.5) - http://sc.communities.msn.com/controls/chat/msnchat45.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{30F86A3A-274F-47F8-9180-568ABBBC1DAD}: NameServer = 192.168.0.1
O17 - HKLM\System\CCS\Services\Tcpip\..\{59B0836B-A135-47C8-A5C6-1740D3B8612E}: NameServer = 213.228.0.23 212.27.32.176

Bonne lecture et merci pour vos réponses.