dearde4n,
I think your problem is coming from a registry hook error related to your winlogon file that came from the virus infection that your anti virus program did not repair right.
There are a number of thing you can do with a windows xp cd to get your system running again.
For one you could do an in-place upgrade, that would keep all you programs and files but you loose MS updates.
You can also use with it to make a bootable cd that will let you restore your pre virus registry, thus letting you login.
IF you can get a windows xp cd the same version as yours then we can repair it.
Otherwise I think you are looking at taking it to a repair shop or format and reinstalling
