|It's extremely RARE for ram that worked fine previously in the same mboard to become "BAD", but it's possible the ram has a poor connection in it's slots and needs to be re-seated. |
However, you have already tried re-seating what I assume is the ram that worked fine before, so that's probably NOT your problem,
Try running the Repair installation of XP procedure.
If the CD loads the intial files fine, then there's probably NOTHING wrong with your ram or it's connection.,
OR - test the ram with a bootable ram diagnostics program !
E.g. Memtest86 or memtest86+ if you have more than 4gb of ram installed, or Microsoft's Windows Memory Diagnostic if you have 4gb or less installed.