System infected most functions disabled

I'd like to say thanks guys for your previous help you are stars.
I'm running winxp service pack 3.
When I was browsing last night I was stung by a virus that I didn't expect.
Avast home detected it but it was too late and the desktop is now almost unuseable; that's why I'm on the laptop now.
To start with, the wallpaper is now "Your system is infected "
Most of the removal options have been disabled including: add/remove progs, ccleaner, Malwarebytes, combofix, ctrl+alt+del.

whenever i try to start these applications I get,"File cannot be executed, file.exe is infected do you want to activate antivirus software."

Antivirus software alerts

False spyware please upgrade to our spyware.

IE open's for vigra and othe spam etc

Please help guys :cry

 

win32:trojan gen System infected most functions disabled

managed to complete a virus scan, avast home edition and it detected;
WIN32:trojan-gen.
I moved this to the virus vault and rebooted but still no joy :cry

help please guys I can't run ccleaner, malwarebytes and I'm getting seriously peeved with the adverts for penile dysfunction :zzz

 

Not trying to bump this just getting more info for you guys.
Can't produce any logs because it's saying files are infected.
The problem is with antivirus live but it's so quick in disabling I can't run any of the progs in the read me.
I can log on, to a differant account that doesn't seem to be infected but I'm scouring the web and nothing seems to be working, pulling my hair out now

 

Re: Antivirus live removal guide

I followed the guide here and now have a malware free computer :-D :-D