Windows XP Blue Screen

I have a Dell Dimension 4600.

My question:  Is this a hardware or software issue?

Following my futile attempt to install an internal DVD-Light Scribe DVD RW drive I have received numerous "Blue Screens".  Booting to safe mode, shutting down and rebooting seems to work for now.

Then last night I could not get the hard drive to boot.  After many frenzied attempts I finally rocked the computer and the thing booted up just fine.  No more blue screen even after repeated shut downs and turn offs.

Thanks - Debora