When a Test Studio project is connected to the (relatively new) TFS service for source control, then you attempt to run your test list remotely (which we are not currently compatible with), what you get is this back:

Failure during test dispatch:
An error occured [sic] while sending the request.
Unable to pass test to web test runner
Failure during test dispatch:
A task was canceled.

Also the CPU utilization on the execution server virtually pegs at 99% (my guess is it's trying to authenticate using Windows authentication for a very long time before finally giving up) for many minutes. The user is left wondering (and inevitably contacts support for help) what the problem is.

This condition needs to be detected and an accurate error message displayed to the user.

P.S. Note the spelling error in the message above.