Have you checked the FAQ / troubleshoot topic?
if you override AA settings via drivers, this might happen.
Please reset them to default or allow application control of AA settings.
Please also check if your graphics card drivers are up to date.
If the problem persists, contact support. (info is also in troubleshoot topic)
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=471076#Post471076
