On Windows 2008 SP2 TMG EMS server MMC shows error "mmc has detected an error in a snap-in. it is recommended that you shutdown and restart mmc" when dashboard is accessed. The observation is that if new Array is created before applying any SP1 this error does not generate. I have updated TMG with SP1,SP1 Update 1, SP2 and hotfixes. Even after applying SP2 the TMG standard is not changed to Enterprise according to KB2555840 which has fixed this issue. This issue is not seen in other 2 Windows 2008 SP2 TMG FW Servers with identical updates Windows 2008 as well as TMG Services Packs.
I have followed this link http://technet.microsoft.com/en-us/library/ff717843.aspx to install and uninstall Service Packs. Tried Windows Update to install Service Packs as well as manual installing of SP2 and related hotfixes. None of the methods resolves the issue. So far none of TMG servers are joined to newly created Array in EMS. This MMC issue, i think is not related to IE9, otherwise other TMG servers would have generated similar error.
TMG installation on all servers is done through Domain Admin account.
Any further diagnostics can be done to troubleshot and resolve this issue.
Thanks