Office Communicator allows you to create groups to sort your contacts. You can also arranged those groups in any order you see fit. So you can move a group that you use frequently to the top of the list, and move others to the bottom. But have you ever wanted to reset that order back to default? Maybe you'd rather have the groups alphabetized. If you have a lot of groups, doing this manually might be tedious. Instead there is an easier way. If you open regedit and navigate to the following key:
If you have moved groups around, you will see the following value. If you haven't moved the groups around, this value will not be there:
If you delete this value, close Communicator, and sign back in, you will see that your groups have been reordered.
*One thing to note is that the Recent Contacts group will always be the first group in the list. You can always turn off the Recent Contacts group if you don't want it shown in the contact list.