Stopping Parallels from opening

I have Parallels 6 on my Mini Mac, specifically for use with some library cataloguing software which I don't use very often. Because I only have 2GB RAM I prefer to run things like Word through CrossOver Mac. But sometimes, by accident, I trigger the opening of Parallels for example when opening a file. When it happens it is so frustrating since I need to wait for Windows XP to load fully and then close it again. Is there any way, even an app, to make Parallels only open with a password or after asking for confirmation?