I just lost over 200 karma in a few minutes and that'll probably continue for awhile. This happens to me every few weeks. Edit: I mean it's been happening every few weeks for a few months for a total of only three or four. Between 400 and 700 karma lost total I think? I don't mean to overstate the problem.

I know the feeling. I get this on average once a month when I'm posting actively. Well, not every comment I have ever made. That would take about 5 hours for someone to do. Just a couple of hundred. About 3 days of karma when commenting actively.