WiFi suddenly unable to connect, router ok

This morning I tried connecting to wifi, but it wouldn't connect, saying that there was "no internet connection", it was working fine yesterday evening. I restarted the modem/router and verified that it was working with 2 other devices. I've tried disabling & re-enabling the wifi adapter, double checked that the wifi button was toggled on, ipconfig release & renew, and a few other things, but nothing has fixed the problem.

At this point if I restart my computer, I can connect to my router for a brief period (< 1 minute) before the connection terminates and won't connect again. The wifi tray icon has a yellow circle on it and I can see the available networks, but I can't connect to them. If I try the windows troubleshooter it will say either to check the router &/or that the LAN is disabled. Running ipconfig -all shows that the media state is disconnected even though it looks to be on/enabled through device manager, the control panel network adapter page, and the keyboard wifi button is on.

How can I figure out where the problem is? It isn't the router since it works with other devices, but it doesn't entirely seem to be the network card either since it can still see the available networks, but just can't connect to them. Does anyone have any idea of what to do?


NIC: Broadcom 43225 802.11 b/g/n. driver version 5.60.350.6

I found a similar posting from another user (Router won't assign network adapter a valid IP address). I basically had the same experience, internet connection was fine one day and dead the next few, during which I threw everything and the box at it but nothing worked, then after giving up in despair, it fixed itself and the internet was working great... so I still have no idea what triggered the wireless/no ip address melt down or what made it start working again... oh well at least it works.