Unremovable Police Virus

Hi Guys,
I have a customers Desktop PC running XP (i am not sure of the service pack)
It has been Infected with the Met police virus and possibly other things. It lets you to the log in screen but when you log in it just comes up with a blank desktop(no task bar or icons). Only once it has come up with the police virus screen and i have not been able to get it to do it since. On the desktop it allows you to open task manager and close programs and processes. I have tried to close every process on the list and it does not have any effect. I have also tried running command prompt through the run command in TM but that only flashes up for a second and disappears. If i try and boot in any of the safe modes as soon as i log in it runs shutdown and their is nothing i can do. and finally i have run 4 bootable Virus removal CD's (Dr Web, Kaspersky Rescue CD, AVG Rescue CD and All of the antivirus Programs is Hirens Boot CD)
I am now desperate to get this sorted. If you know any way to cure this virus (I would really like to avoid a reinstall) that would be great.

Thank you

Ed

tl;dr blank desktop, Police virus, nothing works, HELP!!