Word 2007 stops responding


I have been using Office 2007 Enterprise on my computer for almost 2 years,
and I haven't had any trouble until now. Suddenly, Word stops responding at
the most inconvenient times. Sometimes it won't open at all; other times it
will open and I'll be working on a document, and when I try to save or look
up a word or print or anything like that, the program stops responding and
I've lost everything since the last save.

I installed EndNote X2 citation and bibliography software about a year ago,
but it has worked fine until now so I don't think that's the problem.

I have gone through the troubleshooting guide (though there's not a version
for Vista users - very annoying!) and deleted the data files in my registry
editor, but nothing has helped.

Please tell me there's a solution!
.