Safe Mode and XP installation

Hello,

I am having problem with the performance of my laptop, so i changed the bootup sequence and booted the laptop using safemode. Now system is not accepting password on the safe mode for both users (adminstrator and mine). I
thought reinstalling XP might help but now when the installation starts system gives a message that installation cannot continue in safemode and asks me to restart, this steps is repeating for 5 to 10times.

What can i do in this circumstances to address two issue one is allowing me to login in safemode and installing XP, i appreciate your
help/suggestions.
Weird but true in repair mode my adminstrator password does not work either.
regards
BM