Hi - I haven't checked whether I need to add the environment variable %USERDNSDOMAIN% to my witness server or not, but wanted to let you know your post was by far the most valuable in all I've seen on mirroring issues.

I've been very frustrated with mirroring in general. When everything stays connected it works flawlessly but rarely do things remain connected and so far THREE support calls to microsoft has returned ZERO on our investment. (each call resulted in links to articles that are available for free to the general public with 'case closed' statuses).

Unfortunately my issue is only happening in production so I can't easily makes changes to my environment.

Colleen