Again, are you using ATI radeon cards? If so there are already posts documenting the issue some ATI users are having.
Usualy turning shadows off, and sometimes Bloom as well resolves the issue.
For people to actually attempt to help you, they need details simply saying this is not working, is not going to get your issue resolved anytime soon.
Like this gentleman said, try turning shadow, conversation depth of field and bloom off BUT up your graphics to high (if you have a medium or high level machine this seems to work bes.)