When trying to launch a published application in XenApp 6.x, the following screen appears for a minute, then disappears without launching the application.
This is because the default application launch timeout is set to 60 seconds.
The resolution is to set the timeout to a greater value using the following registry key:
Value Name: LogoffCheckerStartupDelayInSeconds
Value Data: 600
The example above sets the application timeout to 10 minutes. (the value data is in seconds)