I believe I am experiencing the same problem. I'm not too savvy on *exactly * how the GUI works on gnu/linux, but what seems to be happening in my case is that each individual widget (ie a piece of text, link, text entry box, part of a tool bar, the tabs, each individual HTML element) will sporadically blank out. That is, any widget, not just the page itself. I have experienced this problem from day one of installing debian amd64 testing/squeeze on my laptop a couple weeks ago and have gotten by using epiphany instead, however I really miss my firefox plugins :(
This is with iceweasel v 3.5.11 If you want any more information to help squash this bug, don't hesitate to ask!
