I too have had issues with win 7, RDP and the MI424WR Rev I 40.20.1 Firmware .... My workaround is to use teamviewer http://www.teamviewer.com/en/index.aspx You obviously know more than I about this, I gave up rather quickly :smileyembarrassed:
PS are you using RDP 8.0 ??
Update for Windows 7 for x64-based Systems (KB2592687)