(with all the PRV troubles I'veYup had, missing cursors and now random distortion)
I spotted your PRV problems mention like a hawk, because I've been dealing with that also. I think I've nailed it down though. The PRV starts acting crazy, and may even cause a crash,
if you have a midi PGM change somewhere within in a midi track. If you have a the PRV open and set to the same track as one that shows a PGM change, and you either directly move the now pointer to where the PGM change is, or you scroll the PRV near enough it, you start getting a weird refresh and cursor trail in the PRV. If you close the PRV when this happens, and reopen it, you'll see all black. Anyway, whenever you see this strangeness in the PRV window, be sure to 'save' your project immediately -
you're about to bomb.
I've been pulling my hair out and doubting my sanity, but I'm now able to demonstrate and replicate it every time. If I have time tomorrow, I'm gonna do a video screencap and post it on you-tube just to demonstrate the issue.