After syncing your contact database to the HTC HD2 you might notice a significant drop in the stability of HTC's Sense UI. It turns out when you add a contact as a Favorite in the People tab, Sense adds a tag to the Notes field of your contact while also adding that contact to the "HTC Favorite" category. The tag looks like this:

         actionid:CallHome 
    

You'll be able to see that in the notes field of your contacts management software (Outlook). The problem occurs if you've already synced this contact database with a previous version of HTC Sense that also added Favorite tags to your contacts... such as the HTC Touch Pro 2 or Diamond 2, for example. Or it also occurs if the notes field in your Favorite contact already has too many notes and there's not enough room to add the HTCData tag. The problem may appear to fix itself after you do a soft reset, but when the HD2 tries to sync your contacts again, it may freeze up again. There are no problems if you disable the Sense UI.

The fix is pretty simple. Remove all Favorites from the People tab. Then search your contacts from Outlook for contacts with the HTC Favorite category, remove the HTCData tag from the notes field of all of your contacts and clear the "HTC Favorite" category. You should also reduce the length of the notes field for certain contacts. Then sync with the HD2 again. That should give you a clean contacts database.

After you remove all of HTC's old Favorites tags, you should be able to add favorites to your people tab without crashing and your device's stability will be rock solid.