Doesn't seem to be related to playing flash videos. A few moments ago parts of
the screen started looking crazy/corrupted, then on verification again the
flood in dmesg, and I was only able to reboot the machine using ssh. Looking at
cayman bug reports, many people seem to have the same or similar problems. I'll
try a 3.7 or maybe even a 3.6 kernel, perhaps that works reliably.