If your router is the WRT54G, it's a known problem and it drove me mad a couple of months ago. Linksys technical help is pretty good and if you don't have the latest firmware then that is the place to start (it worked for me). Find it at
http://www.linksys.com/servlet/Satel...VisitorWrapper.
There is also some advice in the Linksys technical help (start at
http://linksys.custhelp.com/cgi-bin/...wers.search_nl)
and a search on the Linksys forum (also at the Linksys site) will find dozens of mails. Good luck!