Logfile of HijackThis v1.98.0
Scan saved at 18:48:49, on 23.09.2008
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16705)

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\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Programme\Avira\AntiVir PersonalEdition Classic\sched.exe
C:\Programme\Gemeinsame Dateien\Real\Update_OB\realsched.exe
C:\Programme\Java\jre1.6.0_07\bin\jusched.exe
C:\Programme\iTunes\iTunesHelper.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\Programme\Avira\AntiVir PersonalEdition Classic\avgnt.exe
C:\Programme\Gemeinsame Dateien\Ahead\lib\NMBgMonitor.exe
C:\Programme\Windows Live\Messenger\msnmsgr.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Programme\ICQ6\ICQ.exe
C:\Programme\Avira\AntiVir PersonalEdition Classic\avguard.exe
C:\Programme\Gemeinsame Dateien\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
C:\Programme\Bonjour\mDNSResponder.exe
C:\WINDOWS\System32\svchost.exe
C:\Programme\iPod\bin\iPodService.exe
C:\Programme\Windows Live\Messenger\usnsvc.exe
C:\Programme\Mozilla Firefox\firefox.exe
D:\Valve\Steam\Steam.exe
C:\Dokumente und Einstellungen\Alexander.HOMER\Desktop\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://search.conduit.com?SearchSource=10&ctid=CT1700389
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 =
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
F0 - system.ini: Shell=
F2 - REG:system.ini: UserInit=C:\WINDOWS\system32\userinit.exe,
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - C:\Programme\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Windows Live Anmelde-Hilfsprogramm - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Programme\Gemeinsame Dateien\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Windows Live Toolbar Helper - {BDBD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Programme\Windows Live Toolbar\msntb.dll
O3 - Toolbar: Windows Live Toolbar - {BDAD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Programme\Windows Live Toolbar\msntb.dll
O4 - HKLM\..\Run: [TkBellExe] "C:\Programme\Gemeinsame Dateien\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Programme\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Programme\Java\jre1.6.0_07\bin\jusched.exe"
O4 - HKLM\..\Run: [iTunesHelper] "C:\Programme\iTunes\iTunesHelper.exe"
O4 - HKLM\..\Run: [QuickTime Task] "C:\Programme\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [ATIPTA] C:\Programme\ATI Technologies\ATI Control Panel\atiptaxx.exe
O4 - HKLM\..\Run: [avgnt] "C:\Programme\Avira\AntiVir PersonalEdition Classic\avgnt.exe" /min
O4 - HKCU\..\Run: [BgMonitor_{79662E04-7C6C-4d9f-84C7-88D8A56B10AA}] "C:\Programme\Gemeinsame Dateien\Ahead\lib\NMBgMonitor.exe"
O4 - HKCU\..\Run: [MsnMsgr] "C:\Programme\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [ICQ] "C:\Programme\ICQ6\ICQ.exe" silent
O4 - Global Startup: ATI CATALYST System Tray.lnk = C:\Programme\ATI Technologies\ATI.ACE\CLI.exe
O8 - Extra context menu item: &Winamp Search - C:\Dokumente und Einstellungen\All Users.WINDOWS\Anwendungsdaten\Winamp Toolbar\ieToolbar\resources\en-US\local\search.html
O8 - Extra context menu item: &Windows Live Search - res://C:\Programme\Windows Live Toolbar\msntb.dll/search.htm
O8 - Extra context menu item: Add to Windows &Live Favorites - http://favorites.live.com/quickadd.aspx
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - (no file)
O9 - Extra 'Tools' menuitem: Sun Java Konsole - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - (no file)
O9 - Extra button: ICQ6 - {E59EB121-F339-4851-A3BA-FE49C35617C2} - C:\Programme\ICQ6\ICQ.exe
O9 - Extra 'Tools' menuitem: ICQ6 - {E59EB121-F339-4851-A3BA-FE49C35617C2} - C:\Programme\ICQ6\ICQ.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programme\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Programme\Messenger\msmsgs.exe
O10 - Unknown file in Winsock LSP: c:\programme\bonjour\mdnsnsp.dll
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://update.microsoft.com/windowsupdate/v6/V5Controls/en/x86/client/wuweb_site.cab?1208950553967
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://fpdownload2.macromedia.com/get/shockwave/cabs/flash/swflash.cab
O16 - DPF: {F5A7706B-B9C0-4C89-A715-7A0C6B05DD48} (Minesweeper Flags Class) - http://messenger.zone.msn.com/binary/MineSweeper.cab56986.cab
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WINDOW~4\MESSEN~1\MSGRAP~1.DLL
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WINDOW~4\MESSEN~1\MSGRAP~1.DLL

Siehe meine Antwort in diesem Thread.
Füge dein Log mal hier ein dann müsstest du schon im ersten Eintrag sehen, was zu ändern ist und welche Einträge du fixxen oder genauer untersuchen solltest.