What monitor are you using? Are you using any adaptors to convert the MP output to whatever will fit in the monitor?
If you rang the AppleCare line the first thing they will tell you to do is a SMC and PRAM reset - search the forum for info on how to do those before you go to the effort of reinstalling OSX.
If you bought the MP new, you will be covered under AppleCare too, so don't worry unless this is costing you money because of being a business machine.