assuming you are running it as administrator under 7, 8 or 10
how many clients are you running?
are you using EUO or stealth?
Hi Gimlet, hope you've been well Sir.
Rolled back to Win8 a couple days ago, running as admin and the client normally. Have been using between 2-4 clients simultaneously 95% of the time. I just peeled off the in-box screen protector for stealth today, so I've only been using EUO. For mining, LJ, conc/bandage macro type things. (Oh, and that super spiffy "Miffy's Item Finder"!) Even went so far as to create different profiles for every character. Sometimes the whole loot list just disappears and my assistant.xml file reverts to blank as does the backup. Or what it's doing right at this minute is flat out not looting at all even though the list is showing and the container is correct. Open corpses has been turned off and on, as has been the looter many times.
I'm beyond scratching my head with this. It works amazing, then poof.