After having recurring issues with thumbs for my movies disappearing, I started an investigation to locate the cause of error.
It is annoying having to remove the whole database every time, so I found out it was enough to remove the failing thumbs from .wdtv. But why do they fail?
Last week I made a full copy of all cached thumb files in .wdtv (which just are jpg format, for the record), and calculated check sums for them. Yesterday I added a new movie (in my “New” folder") with a pictures, and everything seemed ok. A few hours later I powercycled the Live with the remote, and the folder thumbnail for the “New” folder and the thumb for the new movie was gone.
The cached thumbs were still present (in .wdtv/thumb/…), with correct time stamp, but the contents was ruined from file position 512 and beyond (3 1/2 K filled with zeroes, then some randomlooking repeating byte sequence). Both thumbs had failed in the same way. I verified the checksums for the other cached thumb files, none was changed.
The cached folder thumb is located (as New.thumb) in another directory than the cached movie thumb, so why is this affected too? It seems that the corruption happens when adding new cached thumbs (i.e. browsing a directory with new movie thumbs).
It is not a drive issue (no errors found), and I have no other corruption problems. I am using the latest nonbeta (and a USB connected drive of course).