Hey I'm having a similar issue here sort of.
I originally installed autoripncompress v2.20 and ripped a DVD as uncompressed WTV, so it can also be played on an Xbox360 extender, and that works great.
For some reason, I can't recall why, I removed AutoRipNCompress and left it off for a month or so. Now I've reinstalled the latest version 2.21 and ripped a couple of DVDs also to uncompressed WTV. I had to also upgrade MakeMKV to 1.7.5. Now these latest rips won't play in WMC and you get the error about the decoder or restart the PC, as the others above are getting. The movies play fine in WMP.
The original DVD I ripped however still plays fine in WMC and WMP so WTF???