after i switch users and go back to the log in screen it seems that if the computer is left for a while and goes to sleep on waking when i log into any account, the screen goes black and stays black. If the computer doesnt go to sleep i can log in after switching users with no issue. so far my only remedy is to restart the computer.. any suggestions?

Joseph - This is a known issue. A number of other people reported the same symptoms. Your only solution at the moment - turn sleep mode off entirely. The programmers are aware of the issue - and I'm sure they're working on a fix.