How do i get rid of Downloader.Exploit.64?

auto protect tells me i have Downloader.Exploit.64, i have followed the instructions on symantecs website but the trojan keeps coming back. Here is my hi jack this log, hopefully someone can help me.

Logfile of HijackThis v1.99.1

Scan saved at 8:21:12 PM, on 2/17/2008

Platform: Windows XP SP2 (WinNT 5.01.2600)

MSIE: Internet Explorer v7.00 (7.00.6000.16608)

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:\Program Files\Intel\Wireless\Bin\EvtEng.exe

C:\Program Files\Intel\Wireless\Bin\S24EvMon.exe

C:\Program Files\Intel\Wireless\Bin\WLKeeper.exe

C:\Program Files\Common Files\Symantec Shared\ccSetMgr.exe

C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe

C:\WINDOWS\system32\spoolsv.exe

C:\Program Files\Common Files\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe

C:\Program Files\Bonjour\mDNSResponder.exe

C:\Program Files\WIDCOMM\Bluetooth Software\bin\btwdins.exe

C:\Program Files\Common Files\Creative Labs Shared\Service\CreativeLicensing.exe

C:\WINDOWS\system32\CTsvcCDA.exe

C:\Program Files\Symantec AntiVirus\DefWatch.exe

C:\Program Files\Common Files\Microsoft Shared\VS7DEBUG\MDM.EXE