Here is my recent aggravation. I have a 755p with verizon. Run a cable sync for calendar and contacts and use push for email to sync with my exchange server.

Any info I enter into my PC and sync works flawlessly to the device.

However, when I put calendar or contact info into my device on a sync it (90% of the time) it won't come over to the PC. After the sync operation, I have to do the required reset and when I go back into the devices contact or calendar item and just change 1 single character (like add a ".") and re-sync it will now work.