Try this solution:
*support.microsoft.com/default.aspx?scid=kb;en-us;297064&FR=1&PA=1&SD=HSCH
Or if that also dont work than..........
start -->> run -->> type this and click ok
sfc /scannow
Insert win XP CD, when asked , and restart after it is completed.
Should solve your problem.
Also refer to these articles:
*support.microsoft.com/default.aspx?scid=kb;en-us;297064
*support.microsoft.com/default.aspx?Product=winxp&scid=kb;en-us;826282
*support.microsoft.com/?kbid=326574