Have you tried on the Win 7 Pro, going in to GPedit, the following key :
Computer Configuration
Admin Templates
Windows Components
Remote Desktop Session Host
Session Time Limits
And see if any of the settings there make a difference?
And also in Start > Administrative Tools > Local Security Policy
Security settings > Local Policies > Security Options > Microsoft Network Server: Amount of idle time required before suspending session. Set it to longer than 15 mins
Computer Configuration
Admin Templates
Windows Components
Remote Desktop Session Host
Session Time Limits
And see if any of the settings there make a difference?
And also in Start > Administrative Tools > Local Security Policy
Security settings > Local Policies > Security Options > Microsoft Network Server: Amount of idle time required before suspending session. Set it to longer than 15 mins