windows repair problem with USB and unsigned driver

Greetings

I seem to have a compound problem with my Dell desktop running windows xp sp2 installation.

After running Microsoft's Live OneCare my system developed what seems to be known as the login/logout loop,

This is where you get to the Select User screen, then when you select user it after a couple of seconds it takes you back to the select user screen.

Safe mode and selecting different users makes no difference, and so doing anything from windows is impossible

This problem seems to have been traced to registry errors, where some malware is removed but the registry still points to it.

So i figured I'd put the repair disk in and run a repair, since my system is unusable at present.

So now my problem is that midway through the repair it comes across an Unsigned driver for my Nvidia graphics card. All i have to do at this point is click yes or no, but at this stage of the proceedings the drivers for the USB keyboard and mouse aren't yet installed (there are no PS2 ports) and so i have no means of selecting yes or no and therefore the repair can't continue.

this page here describes the reason for the repair stop

http://support.microsoft.com/kb/827052/en-us

that page also links to a page of possible solutions

http://support.microsoft.com/kb/314479/

but i really do not understand this, nor how i can make any changes when i can't enter windows

i can access the command line however but don't knw what to do from there

i hope someone can help

At the moment i don't even know how to exit the repair program except by cutting the power which doesn't feel like a healthy option:cry