Spybot S&D finds Win32.Ciadoor.cj, with additional info: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\XPROTECTOR. It removes it but the next time I re-boot, it's back again!
I think "Xprotector.sys" found in C:\WINDOWS\System32\drivers is associated. I have removed this but Win32.Ciadoor.cj still reappears. (It's back in now as deletion made no difference anyway).
AVG comes back clean (in SAFE mode too).
Stinger is clean.
Malwarebytes' Anti-Malware is clean in quick and full scans.
I'm out of ideas now, so thanks for looking.......

Log as follows:
DDS (Ver_09-02-01.01) - NTFSx86
Run by user at 23:34:48.70 on 07/03/2009
Internet Explorer: 7.0.5730.13
Microsoft Windows XP Professional 5.1.2600.2.1252.1.1033.18.503.220 [GMT 0:00]
AV: AVG Anti-Virus Free *On-access scanning enabled* (Updated)
AV: Prevx 2.0 *On-access scanning disabled* (Updated)
FW: ZoneAlarm Firewall *enabled*
============== Running Processes ===============
C:\WINDOWS\system32\svchost -k DcomLaunch
svchost.exe
C:\WINDOWS\System32\svchost.exe -k netsvcs
svchost.exe
svchost.exe
C:\WINDOWS\system32\ZoneLabs\vsmon.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\PROGRA~1\AVG\AVG8\avgwdsvc.exe
C:\Program Files\Norton Ghost\Agent\VProSvc.exe
C:\WINDOWS\system32\svchost.exe -k imgsvc
C:\PROGRA~1\AVG\AVG8\avgemc.exe
C:\PROGRA~1\AVG\AVG8\avgrsx.exe
C:\PROGRA~1\AVG\AVG8\avgnsx.exe
C:\Program Files\AVG\AVG8\avgcsrvx.exe
C:\Program Files\Thomson\SpeedTouch USB\Dragdiag.exe
C:\PROGRA~1\AVG\AVG8\avgtray.exe
C:\Program Files\Norton Ghost\Agent\VProTray.exe
C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Program Files\Wireless Device\Wireless Keyboard\Magickey.exe
C:\Program Files\Wireless Device\Wireless Mouse\MouseAp.exe
C:\Program Files\Wireless Device\Wireless Keyboard\osd.exe
C:\Program Files\Norton Ghost\Shared\Drivers\SymSnapService.exe
C:\Documents and Settings\user.P4\My Documents\My Downloads\dds.scr
============== Pseudo HJT Report ===============
uStart Page = hxxp://www.google.co.uk/
uSearch Bar = hxxp://www.google.com/ie
uSearch Page = hxxp://www.google.com
mStart Page = hxxp://www.google.com
mDefault_Search_URL = hxxp://www.google.com/ie
mSearch Page = hxxp://www.google.com
mSearchAssistant = hxxp://www.google.com
BHO: Spybot-S&D IE Protection: {53707962-6f74-2d53-2644-206d7942484f} - c:\progra~1\spybot~1\SDHelper.dll
EB: {32683183-48a0-441b-a342-7c2a440a9478} - No File
uRun: [MSMSGS] "c:\program files\messenger\msmsgs.exe" /background
mRun: [SpeedTouch USB Diagnostics] "c:\program files\thomson\speedtouch usb\Dragdiag.exe" /icon
mRun: [AVG8_TRAY] c:\progra~1\avg\avg8\avgtray.exe
mRun: [Norton Ghost 14.0] "c:\program files\norton ghost\agent\VProTray.exe"
mRun: [Zone Labs Client] "c:\program files\zone labs\zonealarm\zlclient.exe"
mRunOnce: [Malwarebytes' Anti-Malware] c:\program files\malwarebytes' anti-malware\mbamgui.exe /install /silent
StartupFolder: c:\docume~1\alluse~1\startm~1\programs\startup\enable~1.lnk - c:\program files\wireless device\wireless keyboard\Magickey.exe
StartupFolder: c:\docume~1\alluse~1\startm~1\programs\startup\enable~2.lnk - c:\program files\wireless device\wireless mouse\MouseAp.exe
IE: E&xport to Microsoft Excel - c:\progra~1\micros~2\office10\EXCEL.EXE/3000
IE: {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - {53707962-6F74-2D53-2644-206D7942484F} - c:\progra~1\spybot~1\SDHelper.dll
DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} - hxxp://www.update.microsoft.com/windowsupdate/v6/V5Controls/en/x86/client/wuweb_site.cab?1233270257250
DPF: {8FFBE65D-2C9C-4669-84BD-5829DC0B603C} - hxxp://fpdownload.macromedia.com/get/flashplayer/current/ultrashim.cab
DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} - hxxp://fpdownload2.macromedia.com/get/shockwave/cabs/flash/swflash.cab
Handler: cdo - {CD00020A-8B95-11D1-82DB-00C04FB1625D} - c:\program files\common files\microsoft shared\web folders\PKMCDO.DLL
Handler: linkscanner - {F274614C-63F8-47D5-A4D1-FBDDE494F8D1} - c:\program files\avg\avg8\avgpp.dll
Notify: avgrsstarter - avgrsstx.dll
Notify: igfxcui - igfxsrvc.dll
SSODL: WPDShServiceObj - {AAA288BA-9A4C-45B0-95D7-94D524869DB5} - c:\windows\system32\WPDShServiceObj.dll
============= SERVICES / DRIVERS ===============
R1 AvgLdx86;AVG AVI Loader Driver x86;c:\windows\system32\drivers\avgldx86.sys [2008-5-24 325128]
R1 AvgMfx86;AVG On-access Scanner Minifilter Driver x86;c:\windows\system32\drivers\avgmfx86.sys [2008-5-24 27656]
R1 AvgTdiX;AVG8 Network Redirector;c:\windows\system32\drivers\avgtdix.sys [2008-5-24 107272]
R1 kbfilter;Keyboard Filter Driver;c:\windows\system32\drivers\kbfilter.sys [2005-2-1 12964]
R1 vsdatant;vsdatant;c:\windows\system32\vsdatant.sys [2009-2-5 392824]
R2 avg8emc;AVG8 E-mail Scanner;c:\progra~1\avg\avg8\avgemc.exe [2008-5-24 903960]
R2 avg8wd;AVG8 WatchDog;c:\progra~1\avg\avg8\avgwdsvc.exe [2008-5-24 298264]
R2 vsmon;TrueVector Internet Monitor;c:\windows\system32\zonelabs\vsmon.exe -service --> c:\windows\system32\zonelabs\vsmon.exe -service [?]
R2 XPROTECTOR;XPROTECTOR;c:\windows\system32\drivers\Xprotector.sys [2007-5-22 42848]
R3 SymSnapService;SymSnapService;c:\program files\norton ghost\shared\drivers\SymSnapService.exe [2007-12-20 1553896]
S3 CA500AI;Easy Pix Sv Still Image Capture;c:\windows\system32\drivers\BULK2NM.sys [2005-2-9 11117]
S3 CA500AV;Easy Pix Sv WDM Video Capture;c:\windows\system32\drivers\ca500av.SYS [2005-2-9 492619]
S3 epmntdrv;epmntdrv;c:\windows\system32\epmntdrv.sys [2009-2-12 8704]
S3 EuGdiDrv;EuGdiDrv;c:\windows\system32\EuGdiDrv.sys [2009-2-12 3072]
S4 a2free;a-squared Free Service;"c:\program files\a-squared free\a2service.exe" --> c:\program files\a-squared free\a2service.exe [?]
=============== Created Last 30 ================
2009-03-07 22:55 <DIR> --d----- c:\docume~1\user.p4\applic~1\Malwarebytes
2009-03-07 22:55 15,504 a------- c:\windows\system32\drivers\mbam.sys
2009-03-07 22:55 38,496 a------- c:\windows\system32\drivers\mbamswissarmy.sys
2009-03-07 22:55 <DIR> --d----- c:\program files\Malwarebytes' Anti-Malware
2009-03-07 22:55 <DIR> --d----- c:\docume~1\alluse~1\applic~1\Malwarebytes
2009-02-16 16:41 54,156 a---h--- c:\windows\QTFont.qfn
2009-02-16 16:41 1,409 a------- c:\windows\QTFont.for
2009-02-14 00:36 <DIR> --d----- C:\VProRecovery
2009-02-12 22:02 <DIR> --d----- c:\program files\EASEUS
2009-02-12 20:10 <DIR> --d----- c:\program files\Spybot - Search & Destroy
==================== Find3M ====================
2009-02-05 21:45 4,212 ----h--- c:\windows\system32\zllictbl.dat
2009-01-29 22:54 10,520 a------- c:\windows\system32\avgrsstx.dll
2009-01-29 22:54 325,128 a------- c:\windows\system32\drivers\avgldx86.sys
2009-01-29 22:54 107,272 a------- c:\windows\system32\drivers\avgtdix.sys
============= FINISH: 23:35:30.18 ===============