AMD/ATI have yet another driver update for the 11.11 release.  This is update C of the series and looks to fix issues specifically for the HD5700 video cards.  Snag it...take a breathe...updatee :P

Click HERE or below for update!

http://support.amd.com/us/kbarticles/Pages/Catalyst1111cperformance.aspx

UPDATE:  Link to the actual build on ATI's site is not correct...go to the link below to download the file:
Vista/W7
http://www2.ati.com/drivers/hotfix/catalyst_11.11_hotfixes/amd_catalyst_11.11c_windows_vista_7.exe

XP
http://www2.ati.com/drivers/hotfix/catalyst_11.11_hotfixes/amd_catalyst_11.11c_windows_xp.exe