I've got about 19 AT&T Tilts and 21 Treo 750s (running WM6 and WM5) and randomly Pocket IE will just stop displaying webpages on them, reguardless of what site you visit its just a blank page.

Someone had suggested that its a flaky AT&T proxy on the phone and to remove it, but I'm afraid to do that and break functionality of the device in other places (SMS, MMS, MediaNet, etc) -- does this sound reasonable to try and if so, should I do this and how?

I had a Treo 700wx on the Sprint network and never had this issue. I would have chalked it up to a bad radio on one or two phones, but all of them to it, and both models do it. It's also random when they do it.

Resetting fixes the problems in all cases.