HTC are at it again with the HD2. They are really pushing to make this device work as it should, and eliminate all bugs.
Today we have a new one, "this update for HTC HD2 allows for contacts stored on your SIM card to be properly displayed on your phone along with Phone and Exchange Server contacts". Essentially it fixes an issue with being unable to show/hide SIM Contacts. Prior to this update you could show/hide SIM Contact by applying this which was developed by someone over at xda-developers.
The update is applicable to ROM versions less than or equal to 1.59.XXX.X and since it's a software update, you need to reapply after a Hard Reset.
At present this update is only available on the UK site.
Download the CAB here.