This started happening a couple of months back, I think. Successive updates of Opus - I'm currently on the latest Win64 build - haven't cured it.
When opening a particular folder on my system with the lister in 'Thumbnails' mode, Opus immediately pops up at least one dialog with the text "The error (0xC0000005) occurred in thread 'dopus.thumbgenerate' at address XXX". Opus itself is fine and thumbnailing continues as I'm using 3 threads for it, but one or more of the files - presumably the ones being handled by the crashed thread(s) - don't get their images.
If I leave the 'Save Lister Layout and restart Directory Opus' checkbox ticked and close the dialog, Opus restarts and a thumbgenerate thread promptly crashes again. It's never the same file which causes the crash, and in fact if you ignore the dialog and refresh the lister, all the files will thumbnail normally. Restarting Opus at this point, however, still results in a crash so presumably at least one thumbnail wasn't cached and had to be recreated.
If I keep restarting, eventually it stops happening, but like the original problem this too is unpredictable: it might take a couple of restarts, it might take 10 restarts or it might take so many attempts that I just give up.
So far this is only happening in one folder on my system; the folder contains video files - .mpg, .mp4, .wmv - but there is no consistency as to which one is being processed when the thread crashes. It is just possible that the problem lies with the .mpg files, since those are always the ones which fail to thumbnail, but that might also be simply that the first few dozen files in the folder are all .mpg; the crash occurs pretty much immediately I open the folder and if the first files were .mp4s then I'd see the problem with them instead or as well.
As far as I can see I haven't updated any video codecs in well over a year now, and as mentioned this problem is only a couple of months old so I'm leaning towards it being an Opus bug
Can anyone shed any light, please?