There are currently some problems with Internet Explorer 9 and the Forefront Threat Management Gateway console. After the IE9 installation, the console can be opened but crashes immediately.

The problem is known by Microsoft, but there is no solution at the moment. You should wait with the update until the fix is released.

If you already installed IE9 you can either uninstall it again, or do but the following workaround.

* Open “C:\Program Files\Microsoft Forefront Threat Management Gateway\UI_HTMLs\TabsHandler\TabsHandler.htc”
* Search for the 3 lines which contain “paddingTop”, and remark-out each of them by adding “//” in the begining.
Example: Change the line:
m_aPages [niPage].m_tdMain.style.paddingTop = ((m_nBoostUp < 0) ? -m_nBoostUp : 0) ;
into:
// m_aPages [niPage].m_tdMain.style.paddingTop = ((m_nBoostUp < 0) ? -m_nBoostUp : 0) ;
* Save the file, and re-open TMG management console.

Found at:

http://forums.isaserver.org/m_2002107408/mpage_1/key_/tm.htm#2002107686

Edit:

The problem was solved with SP2 (available here).