One of the first things I always want to know when troubleshooting is "What's changed?"
You indicated that this problem first popped up after installing "Megathemes" (change), so if you haven't already, I would suggest uninstalling that app.
1. After uninstalling Megathemes, test your synchronization to see if you still get the error.
2. If you don't get the error, you can reinstall a freshly downloaded copy of Megathemes (in case the original download is corrupted), and then see if the error returns.
3. If the error does return, and you know that lots of other PPC owners use this app without experiencing this issue, then we can begin to focus our troubleshooting on the Axim. (perhaps other users are experiencing similar issues with Megathemes???)
4. If you're still getting the error after reinstalling a freshly downloaded copy of Megathemes, I would suggest deleting the Activesync partnership on your PC, and create a new partnership.
I was persistently getting a slightly different error message - "1 item not synchronized", and had to finally delete and recreate my partnership to resolve the issue.
Hope this helps,
Scott