Thanks, everyone. 

I update to kernel-2.6.31.6-148, compiz and gnome-shell return to normal. 

I think that I should write a post after searching the FP wiki for radeon and KMS, 

Liang
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<url>http://www.liangsuilong.info</url>
Fight for freedom!!!!(3F)
Ask not what your Linux distro can do for you!
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