Recently I had updated a machine to Windows Vista SP1, and so far have had nothing but good to say about it. One thing I noticed since then, is that when I would Remote Desktop Protocol (RDP) to systems, I would get the "The terminal server has exceeded the maximum number of allowed connections" if others were on it for admin work. Though I had explicitly told the RDP client to connect to the console (session 0) via the command line arguments in the shortcut I created, it did not appear to be attempting to connect to the console session.
I tend to use the console session since the RDP session doesn’t always re-connect to my previous session if I attempt to connect from a different computer, which is a bit of a hassle.
The Shortcut below uses the target of "%systemroot%system32mstsc.exe /console" which worked fine in Windows Vista for forcing the connection to "console". I posted a screen shot of the mstsc options from Vista and Windows 2003 (sp2) where it says the "/console" is the proper switch.
Windows Vista (Gold) RDP arguments
It seems that with Vista SP1, they changed this switch from "/console" to "/admin". So a simple edit to the shortcut, and I am back in the "Admin session". I suppose the difference here is that SP1 is geared toward Windows Server 2008, which doesn’t have the concept of session 0, but it when connecting to a Windows 2003 server "console" and "admin" appear to function the same.
Windows Vista SP1 RDP arguments
Also it looks like I am late to noticing this as others have pointed out this behavior before I, so you can read more about it on Nick MacKechnie’s blog