Copied some data onto a CD, now Windows won't open XP SP3

Had been working mostly fine for several years.

Copied some data onto a CDRW and since then Windows won't go beyond the
first screen. It goes black and stays that way.

I've tried starting in Safe Mode and the Last Known Good Config with no difference.

Haven't had a chance to try booting from the disc (I'm on a work computer right now).
Will try that tonite.

Any idea if the copying had anything to do with it, or might that be just a coincidence.

Either way, any ideas for recovery?

I'm running paid Avira, SUPERantispyware and Malware Bytes, and with a decent
firewall I downloaded from TSpot over a year ago. Never have had anything bad
in the computer for quite some time (per additional manual full scans).

Thanks!