Me too
I have and HP laptop with atheros wifi, and this is happening to me also. I usually plug/unplug my router and the problem is solved. But my thinking, is since this is happening under Vista to me to, is that the TC/IP is getting corrupted. The problem sometimes resolves itself after a few minutes. Running Network diagnostics, it poped up a message about re-setting the adapter. This leads me to belive the problem is in theOS, as I never have this happen under Unbuntu.