If your using RO+HQ (LAV + madVR) you probably know that madVR was updated to 90.16 in MC ver 21.65 (and LAV was updated to .68 in MC 21.58) so if anything changed after MC ver .58 it might be related to these updates. However, I doubt the madVR or LAV updates are the problem, because no one else is reporting having a problem with them.
When you roll back, I don't think the madVR and LAV programs are rolled back. I'm not sure, and I haven't tested this, but I believe I read here that you need to delete the madVR and/or LAV folders then install the rolled-back (to .54) MC version and then let reinstall the "older" madVR and LAV versions that came with .54.
I would try a direct connection the TV to rule out the AVR.
It may also be helpful to try to get a screen shot of the problem so we can see what your seeing.
Good luck.