Secure network causing "server not found?"

I've recently secured my wireless home network connection by making it WPA-personal. It used to be un-secured, but everything worked fine. Though I'm not at all afraid of my next door neighbors having access to my connection, I still wanted to make it secure.

Except it is causing my notebook to get all screwy. It will connect, and then after a few minutes it will take forever to load a page and then it will say "server not found." I don't think it is a problem with my network or my router, cause I'm nowhere close to being out of range (I'm in the same room as the router), and the other notebook computers in my family all work fine.

It might be my firewall. I have sunbelt (free), and possibly the "network security" options were causing my connection to get all messed up. So I'm really not sure how to configure that so I switched back to windows firewall - but I'm still having the same problem.

What is fustrating is that I'll repair the connection and it will work fine....for about 5 mins. Then it will give me the "server not found message."

 

Alright, I also just checked the utility on my Dell TrueMobile WLAN Card. It failed 3 tests - memory test, interrupt test, and loopback test. I talked to Dell support. They told me to replace the card. Expired warantee. Damn.

This isn't the first time my card has died on me without warning. I use my notebook as desktop replacement, so I hardly ever use the card. Could something be wrong with my notebook that is causing the wireless card to die? Or is the lack or use, followed by constant use (now that I'm home from school) causing the prob? When I was trying to set up the network, I was having problems and my connection must have switched on a off a million times....could I have accidentially fried the card that way? Or is it a normal occurance for these cards to stop working after a few years no matter what?