Gene, you're right, I did a Live Update and a big patch was downloaded. (People should check their editor as well - there was an update for the MX-900 editor too!)

I'm still unclear as to what the problem was. I have my MSC-400 control my htpc running SageTV. A number of shortcuts are of the type CTRL+(some key). I've had no problem programming my remote for these, as I said above you just do a macro with CTRL (501) and then whatever key is needed. It works! In fact the Play shortcut is CTRL+D.

The only awkward thing about it is the macro; you're not doing explicitly CTRL+key, you're doing:
CTRL
key

But the remote seems to understand what is meant.

Anyhow... it's always worked for me. So, if something was fixed - what was it?

Edit: just noticed the post by Mike from SurfRemote, most people are probably already aware of the updates, d'oh! :-)