"Internet sharing" dropouts

Hi folks, I'm a PC guy who's been venturing in Mac land lately, specifically since the debut of the iPad. My grasp of the tech is shaky, however.

I've been trying to help my father-in-law with his network connection. Specifically, his iPad connection to his iMac keeps dropping out. We're using the "internet sharing" feature on the mac, and his iPad finds it just fine. But then some random amount of time later it stops working. He has to return to the Mac, uncheck internet sharing, then check it on again, then find it again with the iPad.

This all sounds simple, but for a confused, infirm old guy, it can be a bit much.

His cable connection seems fine, although I'm wondering if he can be getting connection dropouts so brief that he won't quite notice while he's sitting at his Mac, but are enough to kill his shared internet connection. Is there any way of detecting a connection history on his Mac?

Also, if this is the case, is it possible to refresh this 'shared internet' automatically now and then to revive the connection?