[TweedyBird]

Hi,
I have recently experienced the same problems you describe above. I have figured out at least some of the problem and solution.

Part of the problem is that the "Setup/IO" screen in ProTools is a GLOBAL setting, not just for the session you are working on. So, if you screw something up in that screen, all of your sessions will be affected. I'm sure there are reasons to be in there, but unless you know for sure what you're doing, I suggest you leave the "Setup/IO" screen alone with default paths. That means not renaming paths too!. I would like to experiment, but it's too painful to correct mistakes (unless there are ways that I haven't yet discovered)!

Now, the solution is fairly simple and yet tricky. If you get the "input path "S/PDIF L-R" was made inactive because its stem is missing" error, then you have one or more tracks with "S/PDIF L-R" as the input path. If you are looking at the mix window, it will be about 1/3 of the way down where it says I/O. The path will be darkly grayed out indicating it's not a legitimate path. Click on the button, choose interface, and select one of the inputs shown that are legit. On my setup it's either Input 1 or Input 2. Do that for every track that is darkly grayed out. The two tricky parts, to me anyway, are that this also applies to "hidden" tracks, if you have them, and the fact that you can't select "No Input" as a valid selection on the first pass at correcting the error(s). You can check to see if you have hidden tracks by clicking on the |-> (bar right arrow icon) in the lower left hand side of the edit window (or select View-Other Displays-Track List). (Oh, and be sure you do this from the edit window and not the mix window or you'll be stuck with the track list showing every time you open your session. There's a fix for that too, but it also is painful.) Once you click on that icon, the track window appears. All the tracks that are showing in your edit window will have a dark gray dot next to it. Tracks with a light gray dot are not showing, so you have to check those tracks and correctly select an I/O path for those as well. Once you have checked all the tracks, and have entered in a correct I/O path, then save and close the session. When you reopen the session, you should not longer received that error (if you do, you missed a track). Once you reopen the session, you can also set any tracks to "No Input", save and close the session, and it will now be retained.

Hope this helps,
TweedyBird