We have exactly the same problem here:
W7SP1 desktops for users and servicedesk. Mandatory profile for users. When we try to initiate remote assistance we get:
"There was a problem starting Remote Assistance
Remote Assistance is unavailable for the current user account. If you are using a Windows Guest account try logging in with another account. If you are not using a Guest account, try restarting your machine."
When we remove the mandantory profile for the user everything works great.
I tried the fix with the registry key but that didn't work.
I'm open for ideas,
Found what I was doing wrong: I put the regkey with sid of the servicedesk group in the profilelist. I needed to change the created registerkey of the logged in user. After manualy changing the \State=0 it works again.
Now I am looking for a way to implement this in the preferences part of the GPO
