coherence in grey (parallels 7 - windows xp)

Hello I upgrate to parallels 7 and I cannot choose the coherence mode anymore as i could before, it stays in grey. i am not at all a computer geek and also my parallel is in french, so if you have an easy way to do this please explain me !!
thank you so much

 

What you should try for sure - is to reinstall Parallels Tools. Go to Virtual Machine menu --> reinstall Parallels tools. If it does not help - use this kb www.kb.parallels.com/8969