Sorry to upset you Vikas, but think I owe it to dont70. Why do you suggest recreating the Preferences (losing all customisation, something you never warn about) for a bug that is well-known in CP6.01 and has been fixed in 6.1? There are a lot of threads around that do complain about this flickering of shapes (and I even got a technical explanation about its origin months ago by an engineer). I was one of the first to point to it and it was fixed, such a pity that the bug patch promised to non-subscription users is still not there.
Here is one example of a thread: http://forums.adobe.com/message/5231609#5231609
If you can explain me why recreating Preferences could possibly solve such a bug, I will apologize for my rudeness. But since you are from the staff, I think it is important not to push users to non-working solutions.
Lieve