If a group name is associated with a Fundraiser group then it wont allow the name of the group to be edited.
We are currently evaluating this issue for a fix in a future service pack
Steps to Duplicate
1. In CRM click on the constituents tab > Constituents > Constituent search 2. Click the chevrons to show advanced search option, then check Groups/Households 3. Click search 4. Choose a group and click on the name 5. Once on the group page click on Edit group - is a group that can't be changed -"Fundraising group" you cannot edit it