I've noticed significant improvements since 8.0.293. I'm now using 315 (I haven't gotten around to updating to 318 yet), and things are a lot better.
I still have Norton running, but MJ "almost never" deletes my files any more... many of them the same files that it did delete the first time around. However, it still does get rid of one here and there, so I am very careful when I am updating tags. I keep a Window's Explorer window open to the directory I'm tagging so that I can see if one of the files becomes tiny after tagging it (like Sudadon said, it writes a tiny non-playable file). If this happens, then I use Norton to recover it.
A couple of the files it has deleted since the upgrades have only had ID3v1 tags, and I thought this might have something to do with it... but I later noticed that it did it to a couple files with ID3v2 tags as well... which would seem to disprove the first theory.
I checked to see if the files were read only.... they were not. They were not in use by any program. They were not currently playing. I wasn't doing anything odd like cancelling the process. Just putting in the appropriate artist, or updating the name of the song.
I should note that I've never had any problem renaming/moving the actual file... just the tags.
All in all... the whole tagging problem is much improved... but still a pain because I have to keep an eye on every file I ever update... just in case.
I have used many music players/jukeboxes, but none compare to MJ. This annoyance won't make me stop using MJ... but it would be REALLY nice if I didn't have to worry about it deleting things.
That's my two-bits.
But Sudadon, have things improved much for you? or not at all?