At the moment I have problems with LockRect / UnlockRect, described here: http://archives.free.net.ph/message/20060213.220622.51814d8e.en.html (The sf.net archives broke the attachmet). This is needed for DDraw, and it's also a showstopper for many D3D7 games.
Hmm, what application are you using to test this? (if you haven't already fixed the issue).