Error message when you send an instant message to a distribution group that contains more than 100 members in Communicator 2007: "<GroupName> is too large to display"

When you send an instant message (IM) to a distribution group that contains more than 100 users in Microsoft Office Communicator 2007, you receive the following error message:

This problem occurs because Communicator 2007 has a limit of 100 members in a distribution group. Additionally, Communicator 2007 has a limit 100 attendees for a conference.

Hotfix information

To resolve this problem, apply the Communicator 2007 hotfix package that is dated December 7, 2007. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Note After you enable the hotfix, the limit is increased from 100 to 150.

Registry information

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To enable the hotfix, you must change the registry. The changes to the registry can be made through a Group Policy object (GPO).

To make the changes to the registry manually, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry key:
   HKLM\Software\Policies\Microsoft\Communicator
3. Right-click Communicator, click New, and then click DWORD Value.
4. Type MaxDLExpansion.
5. Right-click MaxDLExpansion, and then click Modify.
6. In the Value data box, type 150, and then click OK.
7. Locate the following registry key:
   HKLM\Software\Policies\Microsoft\Communicator
8. Right-click Communicator, click New, and then click DWORD Value.
9. Type MaxConferenceSize.
10. Right-click MaxConferenceSize, and then click Modify.
11. In the Value data box, type 150, and then click OK.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.