Installed Lion, change wallpaper, "desktop & screensaver" freeze, force quit, then "system preferences" freeze and need force quit every time

After Lion install, tried to change wallpaper in "system preferences"->"desktop & screensaver" appeared but immediatly freeze, so force quit.

Then System preference pane as it immediatly freezes if I try to open it. Have to "force quit" each time.

Found many people have the exact issue and highly likely it's the bug of lion.

Anybody found a solution? Thx.