Win XP reboots

I have 1 pc2100 256MB stick in my system. I run Windows XP with SP2. When I install another pc2100 256MB stick for 512 MB of total ram, the computer boots up fine to start. But after a 5 ot 6 boots, Windows XP continually reboots itself. After the intro screen stating Windows XP with the 3 blue bars (with SP2) moving across the screen, the computer does not go to the welcome screen but reboots itself starting at the bios again.

When I remove the extra ram, the system works perfectly.
What can I do or fix or check?

Thanks,
acampbell1

Thanks Rook,

You were right! The memory stick was bad.
Thanks for solving that problem

acampbell1

<P ID="edit"><FONT SIZE=-1><EM>Edited by acampbell1 on 01/15/05 04:46 PM.</EM></FONT></P>