Wireless "fails" after a few minutes.

I have an HP Paviion dv8500 with a Broadcom 802.11 b/g/n mini-PCI card. I recently replaced the motherboard and reinstalled Windows 7. Win7 picked up the card during the install, and successfully applied the updates during installation, as well as dling drivers for other devices.

However, I noticed that after "awhile" (ranging from 30 minutes to a few hours), the wireless card stops reciving signal. I can still see the networks, but it doesn't let me connect. I restarted my router and nothing. I restart my computer and it connects automaticallly, but then after " while", it stops getting signal.

Figuring it was maybe hardware related, I plugged in a spare USB wi-fi adapter I have. At first, it looks promising, but its repeating the same behavior as the internal card.

These are two diff cards made by two different OEMs with two different drivers and using two different hardware interfaces, but the same bevhaior. Do think its hardware, or is it something wrong on Windows? if it is Windows, any suggestions?