Are you using google chrome? chrome has not worked well on a lot of XP computers.
you can try deleting chrome and reinstalling it, but the same thing may happen again.
If you are using chrome, click my computer, click control panel, click add remove programs, look on the list for chrome, delete it.
restart the computer and if you want, reinstall chrome.
But you may find that firefox works more stable with XP systems, and you may not want to use chrome on an XP computer.