Local Only Unidentified Network Issue

I'm having an infrequent issue with my wireless adapter being able to
connect as "local only" and "unidentified network" - the result is no
Internet. As I have an XP box that uses the same router, I'm able to
verify the problem is just with with my Vista (32 bit) laptop, and it
uses a Dell Wireless 1390 WLAN Mini-card which connects to a Linksys
WRT54G router. I'm unable to determine the cause or duplicate the
problem but when it happens, the only solution that works so far is to
uninstall / reinstall the adapter from the device manager. Any advice
to help track down the problem and resolve it without uninstalling?