Mozilla and Mozilla Firefox has a flaw:
http://www.eweek.com/article2/0,1759,1621463,00.asp
The fix is here, just click the install link and you're done:
http://update.mozilla.org/extensions...nfo.php?id=154
EDIT: Turns out that this is a flaw in the WindowsXP OS which is fixed in SP2, not a flaw in Moz.
Also, I found this article interesting, seeing as it's on a Microsoft site:
http://slate.msn.com/id/2103152/