Suddenly my workstation wouldn't accept incoming remote desktop sessions. I first thought it was because I was connecting from a Vista computer, but as it turned out, I couldn't even connect from other 2003 servers. The event log only said this:
Application popup: : \SystemRoot\System32\RDPDD.dll failed to load
Which was not very helpful! After googling around quite a bit, I had tried reinstalling the RDP software's latest version and rebooted, when I found multiple people describing the same problem and fixing it by removing their ATI video drivers... As I have a nvidia card, I first thought it had nothing to do with this. However... there wasn't much else to try. I uninstalled the Asus Enhanced Video Driver and the nvidia drivers - and then it worked. Crazy. Worst part is, now I've reinstalled the video driver, and remote desktop still works. Huh.
So it could be that Asus Enhanced Video Driver is the culprit. I won't try and find out.