A very strange behavior occured the last days. A customer is using Windows Server 2008 with TS Web Access and TS Gateway enabled. When he tried to access his TS Web Access site he was asked for the password and then nothing happend. The browser was loading the website and after one or two minutes the TS Web Access site showed up with no icons for the applications in it.
It was possible to workaround that problem be running ‘iisreset’ but only for maybe 30 minutes and after a while it didn’t help at all.
I created a test site to check whether the problem was IIS related – but it wasn’t. The testsite showed up in not time.
Connecting to the server with TS Gateway Services worked without any problems.
I checked the TS Web Access Configuration on the server just to find that the same behavior occured there, too.
Time to open a case with Microsoft.
Meanwhile I sniffed a littlebit around with Procmon to see if there was anything special. I could see that the WMI-service took a lot of time to read the shell32.dll from an UNC-path. The enlightenment came when MS-Support told me that the icons for the applications in TS Web Access are enumerated by the WMI-service. The support asked me to check this registry key:
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Terminal Server\TSAppAllowList\Applications
Within this regkey all published application are listed and the have a string value called “IconPath” – this was pointing to an UNC-Path instead of a local path.
After changing that path to a localpath (e.g. %systemdrive%\…) the problem went away.