If you create a user that is part of the Administrators Group with read-only access rights to FSOCS, when that user logs on and tries to open the Forefront Server Security Administrator, the following message appears “ERROR: Unable to connect to service. An error was returned. Location: CocreateInstanceEx.Error: Access is denied”.
To work around this problem, follow the below instructions:

1) Click Start
2) Click Run
3) Type DCOMCNFG.
4) Expand Component Services
5) Expand Computers
6) Expand My Computer
7) Expand DCOM Config
8.) Right click on FSCController and click Properties
9) Click the security tab
10) In the Launch and Activation Permissions section click Edit
11) Add domain users and then Allow for Local Launch, Remote Launch, Local Activation, and Remote Activation.
12) Click OK and OK again