Guys, I've been following this thread as I too have the USB issue with my brand new MSI P35 Platinum, and I'm on the verge of returning it.
While searching the MSI Forums, I found this article regarding the tenth pin on MB USB connectors creating all sorts of problems.
http://forum.msi.com.tw/index.php?topic=57472.0
Does anyone think this issue relates to our problem here?