...I recommend the following steps to ensure a clean Treo:
1. Hard reset the Treo.
2. Disable all conduits except Address Book, Memo Pad, Date Book, & ToDo's. Make sure the Install and Backup conduits are unchecked.
3. HotSync the Treo.
4. Make sure all data you want to keep is on the Treo.
5. Uninstall Palm Desktop from your computer. Wipe away all traces including all prefs & user data.
6. Reinstall Palm Desktop (you may need to set up a new user).
7. Repeat step 2, but set the conduits to "Computer overwrites handheld."
8. HotSync the Treo.
9. Confirm your data is on the Treo.
10. If performing Treo firmware updates, only use Verizon updates (although I have strong reservations about doing it).