usually when it's cyclical like that, it's something running in the background--often some sort of automatic update/renewal process kicking off on a schedule. The trick is in narrowing it down. Can't say for certain it was the auto update side of the Geforce management software... but it's possible I guess. Worth a shot, and it's not too hard to manually check for updates if removing it provides relief from disconnects.

You may be having issues with the wireless as well. Some have had some funkiness in Win7 with wifi drop-offs. Not sure it's been hourly though.