I manually import hands out of folders. The last time I did so , about 1/3 of the hands out of a mixed batch of FTP and Stars hands were import errors. Today, I tried a different batch of hand histories from a different FTP username, and none of them imported properly; all 500+ hands were listed as import errors.
I use Parallels to run Holdem Manager on my mac, and lately I've been having to reenter my license code frequently upon restarting Parallels. I don't know if that has anything to do with it.