I'm experiencing the same problem. Midori loads fine and shows its startup page, but if I try to load Facebook or something, it locks up instantly. I'm not sure that the bootc kernel is the problem, though, because the first time it happened, I was trying to download the bootc kernel deb. So I'm pretty sure I was on the kernel that comes in the Raspbian image (I was using Hexxeh's image)
Box seems to run fine in text mode. Haven't gone into depth trying different software combinations, but it is very frustrating. I might be looking for a warranty replacement if I can't find a setup that's stable on my board.