Are you using gfxpayload=keep in your grub config?  If so does it help if you
remove it?  Can you also try a 3.8 kernel?  Specifically this patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=6253e4c75d96006c06b9ac8f417eba873de2497b