UltraVNC

Have you tried this:

Open up the Local Group Policy Editor (gpedit.msc) on the Win7 workstation.
Go to: Computer Configuration> Windows Components> Windows Logon Options
Double click Disable or enable software Secure Attention Sequence and select Enabled
In the drop down box under Options: choose ...

I have a group that I add to the MS Logon Groups (uvnc_settings.exe), but when I add this group to the #1 position then local administrators can't connect to the machine by remote.
If I move the group to the #2 position then the those people plus the local admins can connect.

This was not an issue ...