When you say the other two machines don't have a DRM folder, are you sure it's not just "hidden" as pointed out in that sticky thread I linked to?
A Duh Moment on my part. I assumed I was seeing all hidden files because I could see the ProgramData folder, but I didn't have the Hide Protected Operating System Files box unchecked. So it turns out all machines have DRM folders.
Are they all Windows 7?
Yes.
The "ResetDRM" method was the 3rd method to try. Did you run through the first method, where you rename or delete the DRM folder and then go to that Microsoft website and click the "Update" button?
I tried to run through all three methods, but here's what happens:
Method 1: Run windows media player DRM troubleshooter and check what is causing the problem.There is no Windows Media Player DRM Troubleshooter in the list. I have Windows Media Player DVD, Windows Media Player Library, and Windows Media Player Settings. I've run all three of these on all three machines. No impact.
Method 2: Rename DRM folder, this forces Windows to build a new one.At first, I couldn't rename it because the folder was in use by another program. So I skipped to Method 3. I eventually was able to shut down enough processes and services to get it to rename but when I got to the site - in IE running as Administrator - the Upgrade button was grayed out and clicking on it didn't do anything. So I just tried playing a song from the PS, and that would cause the DRM folder to be recreated, but still no love.
Method 3: Use the ResetDRM ToolI downloaded and ran the tool. It says it ran successfully. It created a new DRM folder, it said Clean DRM Succeeded, it still doesn't work. BTW, there is a sample WMA file with DRM on this site that you're supposed to use for testing. I downloaded it and MC cannot play it before or after the ResetDRM.
I've done this step multiple times now. Same result.
So this definitely seems to be DRM related, but I can't think of anything else to do to fix it.