Probleme de trojan ou de spyware

Comme beaucoup ma page d'acceuil est sans cesse modifiée et des messages me signalent la présence de trojan ou spyware...
Merci de bien vouloir m'aider à l'éliminer... pour info je suis en windows 98. Par avance, merci !!!
j'ai donc lancé l'analyse HIJACKTHIS dont voici le résultat :
Running processes:
C:\WINDOWS\SYSTEM\KERNEL32.DLL
C:\WINDOWS\SYSTEM\MSGSRV32.EXE
C:\WINDOWS\SYSTEM\SPOOL32.EXE
C:\WINDOWS\SYSTEM\MPREXE.EXE
C:\WINDOWS\SYSTEM\mmtask.tsk
C:\WINDOWS\SYSTEM\MSTASK.EXE
C:\PROGRAM FILES\FICHIERS COMMUNS\MICROSOFT SHARED\VS7DEBUG\MDM.EXE
C:\PROGRAM FILES\SYMANTEC_CLIENT_SECURITY\SYMANTEC ANTIVIRUS\RTVSCN95.EXE
C:\PROGRAM FILES\SYMANTEC_CLIENT_SECURITY\SYMANTEC ANTIVIRUS\DEFWATCH.EXE
C:\WINDOWS\SYSTEM\MSDTCW.EXE
C:\WINDOWS\SYSTEM\RPCSS.EXE
C:\WINDOWS\EXPLORER.EXE
C:\WINDOWS\TASKMON.EXE
C:\WINDOWS\SYSTEM\SYSTRAY.EXE
C:\WINDOWS\SYSTEM\KHOOKER.EXE
C:\WINDOWS\SYSTEM\HPSJVXD.EXE
C:\WINDOWS\SYSTEM\STIMON.EXE
C:\PROGRAM FILES\HEWLETT-PACKARD\HP PRECISIONSCAN\PRECISIONSCAN PRO\HPLAMP.EXE
C:\PROGRAM FILES\SYMANTEC_CLIENT_SECURITY\SYMANTEC ANTIVIRUS\VPTRAY.EXE
C:\WINDOWS\SYSTEM\PWSTRAY.EXE
C:\PROGRAM FILES\A4TECH\MOUSE\AMOUMAIN.EXE
C:\WINDOWS\SYSTEM\GSICON.EXE
C:\WINDOWS\SYSTEM\DSLAGENT.EXE
C:\WINDOWS\SYSTEM\IPCFG.EXE
C:\WINDOWS\SYSTEM\CTFMON.EXE
C:\WINDOWS\WINPOPUP.EXE
C:\WINDOWS\SYSTEM\WMIEXE.EXE
C:\PROGRAM FILES\MICROSOFT OFFICE\OFFICE10\WINWORD.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\WINDOWS\SYSTEM\DDHELP.EXE
C:\WINDOWS\SYSTEM\INETSRV\INETINFO.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\PROGRAM FILES\INTERNET EXPLORER\IEXPLORE.EXE
C:\1CLICKUNZIP_UNZIPFOLDER\HIJACKTHIS.EXE

R1 - HKCU\Software\Microsoft\Internet Explorer,SearchURL = www.cc-beaufort-en-anjou.fr
R1 - HKCU\Software\Microsoft\Internet Explorer,(Default) = http://fastsearchweb.com/srh.php?q=%s
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Bar = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,Default_Search_URL = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,SearchAssistant = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R1 - HKCU\Software\Microsoft\Internet Explorer\Search,CustomizeSearch = about:blank
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = res://C:\WINDOWS\SYSTEM\SNNPAPI.DLL/sp.html (obfuscated)
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch = about:blank
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,SearchURL = http://my-search4u.com/sp.htm
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,HomeOldSP = about:blank
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
R3 - Default URLSearchHook is missing
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\PROGRAM FILES\ADOBE\ACROBAT 5.0\READER\ACTIVEX\ACROIEHELPER.OCX (file missing)
O2 - BHO: (no name) - {9D441CD2-443C-40C7-82F0-E8442EA3568D} - C:\WINDOWS\SYSTEM\SNNPAPI.DLL
O3 - Toolbar: @msdxmLC.dll,-1@1036,&Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\SYSTEM\MSDXM.OCX
O3 - Toolbar: (no name) - {06ABAA2D-34AB-4902-A326-409BD9B9A7A5} - (no file)
O4 - HKLM\..\Run: [zzzHPSETUP] E:\Setup.exe
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: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\Run: [SiS KHooker] C:\WINDOWS\SYSTEM\khooker.exe
O4 - HKLM\..\Run: [HPSCANMonitor] c:\windows\SYSTEM\hpsjvxd.exe
O4 - HKLM\..\Run: [StillImageMonitor] C:\WINDOWS\SYSTEM\STIMON.EXE
O4 - HKLM\..\Run: [HP Lamp] "C:\Program Files\Hewlett-Packard\HP PrecisionScan\PrecisionScan Pro\hplamp.exe"
O4 - HKLM\..\Run: [vptray] C:\PROGRA~1\SYMANT~1\SYMANT~1\vptray.exe
O4 - HKLM\..\Run: [PWSTray] PwsTray.exe
O4 - HKLM\..\Run: [WheelMouse] C:\PROGRA~1\A4TECH\MOUSE\AMOUMAIN.EXE
O4 - HKLM\..\Run: [GSICONEXE] GSICON.EXE
O4 - HKLM\..\Run: [DSLAGENTEXE] DSLAGENT.EXE
O4 - HKLM\..\Run: [ipcfg.exe] C:\WINDOWS\SYSTEM\IPCFG.EXE
O4 - HKLM\..\Run: [scands32.exe] C:\WINDOWS\SYSTEM\SCANDS32.EXE
O4 - HKLM\..\Run: [XPSP2 Firewall] C:\WINDOWS\system32\xpsp2fw.exe
O4 - HKLM\..\RunServices: [LoadPowerProfile] Rundll32.exe powrprof.dll,LoadCurrentPwrScheme
O4 - HKLM\..\RunServices: [SchedulingAgent] mstask.exe
O4 - HKLM\..\RunServices: [MDM7] "C:\PROGRAM FILES\FICHIERS COMMUNS\MICROSOFT SHARED\VS7DEBUG\MDM.EXE"
O4 - HKLM\..\RunServices: [MSDTC] msdtcw -start
O4 - HKLM\..\RunServices: [RNBOStart] C:\WINDOWS\SYSTEM\RNBOSENT\SENTSTRT.EXE
O4 - HKLM\..\RunServices: [rtvscn95] C:\PROGRA~1\SYMANT~1\SYMANT~1\rtvscn95.exe
O4 - HKLM\..\RunServices: [defwatch] C:\PROGRA~1\SYMANT~1\SYMANT~1\defwatch.exe
O4 - HKCU\..\Run: [ctfmon.exe] ctfmon.exe
O4 - HKCU\..\Run: [Windows Update Client ] C:\WINDOWS\system32\wuclient.exe
O4 - Startup: Winpopup.lnk = C:\WINDOWS\WINPOPUP.EXE
O4 - Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://c:\PROGRA~1\MICROS~2\OFFICE10\EXCEL.EXE/3000
O9 - Extra button: Related - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINDOWS\web\related.htm
O9 - Extra 'Tools' menuitem: Show &Related Links - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINDOWS\web\related.htm
O12 - Plugin for .mid: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin2.dll
O12 - Plugin for .mov: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin.dll
O12 - Plugin for .mpeg: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin3.dll
O12 - Plugin for .mpg: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin3.dll
O12 - Plugin for .png: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin5.dll
O12 - Plugin for .mp3: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin4.dll
O12 - Plugin for .htm: C:\PROGRA~1\INTERN~1\PLUGINS\nppdf32.dll
O12 - Plugin for .tif: C:\PROGRA~1\INTERN~1\PLUGINS\npqtplugin6.dll
O16 - DPF: {74D05D43-3236-11D4-BDCD-00C04F9A3B61} (HouseCall Control) - http://a840.g.akamai.net/7/840/537/2004061001/housecall.trendmicro.com/housecall/xscan53.cab
O17 - HKLM\System\CCS\Services\VxD\MSTCP: NameServer = 193.252.19.3,193.252.19.4
O18 - Filter: text/html - {550C92B7-AF0E-44F8-81FD-AFAD5D4A222C} - C:\WINDOWS\SYSTEM\SNNPAPI.DLL
O18 - Filter: text/plain - {550C92B7-AF0E-44F8-81FD-AFAD5D4A222C} - C:\WINDOWS\SYSTEM\SNNPAPI.DLL

Cordialement

Antony