Have you done any kind of rooting or flashing of custom roms on it?
If so make sure you have cleared your data and cache.
If you haven't rooted and flashed a custom rom I suggest you do so as the Droid X stock is very buggy for some reason.
It is my personal phone and once I rooted it and put a custom rom on it I couldn't of been happier.
Check out my blog, I have an application download there for one click rooting. I'll be happy to help anyway i can."
Not only am I now going to be a constant reader to his blog, I am going to fix this annoying problem. THANK YOU!!!!