XP ends right after start

Hello,

while trying to perform a system rollback to a prior date (without an urgent
cause), I ecperienced this problem:

Since the rollback routine tried to launch Windows again, there is a forced
logout immediately after a very short display of the empty desktop. This
also occurs in protected mode, even when I try to login as administrator.

Maybe the rollback routine throws me out, but it could also be just a
coincidence and there is a virus ore something like that on my computer
(protected with Kaspersky). Or is it something completely different?

Thank you for any help!

Best, Emil