I've got a Dell studio1555 that has been giving me fits with wireless networking oddities.
Laptop was running vista home premium & i upgraded to win 7, as that wasn't the first vista laptop that had weird wireless problems. Right after the upgrade (custom, did fresh install on reformatted HD), it detected the wireless network in the office & connected fine. Was going through windows updates, as well as Dell driver updates & at some point, it disconnected & couldn't connect to network. Windows troubleshooting suggested rebooting the router & since that wasn't an option, I got out my Verizon jetpack & connected to it. all worked fine for a while & then suddenly that could no longer connect to the internet. Windows troubleshooting suggested the same fix, but since my mac laptop was still connected to jetpack & internet was working fine, I thought it was something else. Got back home & once again, it found my home wireless network, worked for a while & then eventually the same problem - can't connect to my wireless network! Laptop wireless is the intel wifi link 5100 AGN & I do have latest drivers from dell.
What could be the problem?