ActiveSync has been known to toss out a confusing error message on a very rare occasion. If you've ever been stung by this unfortunate event, you'll want to bookmark Chris De Herrera's web page that details a large number of the error codes, what they really mean, and how you can fix them. As any good resource, it's a work in progress. So if you've had a problem that's not listed on their, you might want to let Chris know so he can add it.
"I have no special talents, I am only passionately curious" - Albert Einstein