Treo 650 Calendar Problem, Resets if you change Category Color

I have a Treo 650 happily for over a year, but recently i got this problem:

In the Calendar app, i go to the list of categories, edit, and want to assign a color to a category. The Treo resets. It happens everytime i try it!

I've found that the trick is simply to set hotsync for Calendar to PC overwrite Handheld. That's it! No need for hard reset etc! Hope this helps someone else if they face this problem.