Distribution Group manager can't modify group

Question

Setup
MS Exchange 2010 version 14.3 (Build 123.4)
Distribution Group is a Mail Universal Distribution which has less than 20 members total
There are three managers in the "Managed By" listing.  Of these two can modify the list, the third cannot.  When the third manager tries to modify the list they get the following error:
The Public Group cannot be displayed.  The connection to Microsoft Exchange is unavailable.  Outlook must be online or connected to complete this action.
Note: The user is connected to the Exchange environment as evidenced by the "Connected to Microsoft Exchange" in the lower right portion of his Outlook 2010 window.  He is also hardwired into the network,
ie no wireless connection.  He tried the going in through OWA and got the same error as above.  
Any ideas on what I can check to see why this manager cannot modify the list whereas the other two can? 
nc

Answer 1

Hi ncouch55,
If there are multiple GCs in organization, We could refer to the following link to choose the closest GC for the specific user:
1). Click Start, and then click Run.
2). In the Open box, type regedit.exe, and then click OK.
3). Locate and then click the following key in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Exchange\Exchange Provider
Note You may have to create the registry path.
4). On the Edit menu, click Add Value, and then add the following registry value:
Value name: GC Server
Data type: REG_SZ (string)
Value data: the FQDN of the closest GC server
5). Quit Registry Editor.
If the issue persist, we could clear manager on distribution group and re-grant permission to three manager.
If there are any questions regarding this issue, please be free to let me know. 
Best Regard,
Jim