Newbie to linux mining.

i have 5 sapphire 7950 setup last night to mine ltc in xubuntu 12.04. After 6 hours mining, I believe one gpu gets crashed and xubuntu never gets recovered from the crash since now I can only see 4 graphic cards using command

sudo aticonfig --adapter=all --odgt


I also noticed that my xubuntu desktop is abnormal, since the color in the background looks like its in the middle of a crash.
Anyone can help me diagnose the issue??