It was working fine when I left work yesterday... got here this morning and ActiveSync now briefly connects, then pops up a dialog that says:
"Synchronization cannot be completed successfully. Disconnect your device and try again. If this problem persists, see the Microsoft ActiveSync Troubleshooter in Microsoft ActiveSync Help on your desktop computer."
Of course, the troubleshooter was no help at all. I tried everything it suggested... I've been through reinstalling ActiveSync (got version 3.8 while I was at it), deleting the partnership and recreating it, uninstalling the USB device and letting it redetect... all of these things worked fine... but it still refuses to sync. I didn't do anything out of the ordinary with it last night... didn't install any new software at home or anything... it just didn't work when I got here this morning.
I have yet to do a hard reset. I guess that's next. Wonder when my last backup was.