Vista - compter doesn't pick up wireless network

About a week ago I started having difficulty connecting to our wireless network. The caution sign would show up then disappear leaving the 2 cpu icons, but the globe wouldn't show up and I had no internet. I would diagnose and repair which would prompt me to reset network adapter, after this was complete i was able to connect. One day it didn't work, I tried restarting modem, router restarting computer, which usually works but not this time. I would open up availabe networks and "linksys unsecured" was the only thing that showed up. I didn't see our network or our neighbors which usually shows up. I tried removing the network, might i add is my roommates, and she is able to connect w/o problems, but I wasn't able to add it again, which in the past it has worked successfully. It's a linksys WRTG54 router and I have dell vista inspiron 531. I can connect directly from the router fine, but no wireless. I attempted to connect to the linksys unsecure network and it said it was successfully connected but I did not have internet. Things I've tried:
went to the routers web address and was able to secure the linksys network for a day but still wasn't able to get internet, connected w/o internet access. eventually said "settings saved on this computer for the network don't match requirements of that network" instead of secured/unsecured.

put in the LELA disk and was unable to find a problem the first few times through. I tried it again today and it said my wireless radio adapter was turned off. Fn + F2 to activate but my keyboard doesn't have an Fn key, tried all keys left to right of the spacebar. not sure exactly what the function key is on this dynex keyboard. is there another way to turn on the radio adapter? or do you think this could be the problem?

The only thing i can think of now is changing the IP address, but I didn't want to do this until i was sure that may be the problem. Also my firewall doesnt appear to be the issue. The router is no longer under warrantee, but I'm almost sure it's my computer. I've searched for days on forums w/o any luck. If you have any suggestion as to what the problem may be I'd appreciate the feedback thanks.