My MC 5 just stop responding
 

After having a Video Mix Down, I turn off the computer. Next day when I turn it on, My windows said that My computer was shut down improperly and needed to make choice if I want to run in safe mode or start normally. I chose start normally, then My MC 5 cannot run properly, like; it can play back audio only for few seconds on the timeline...
Does anybody experience this, it could be from Windows or MC?

Thanks.