I also had the same problem - thanks much for the original post, jvsantosgt, and of course, thanks to jholder for the fix!
I've got several servers running, ALL but one of which lost zmlogger somewhere along the line, I think in 5.0.10.
After doing a "killall -9 zmlogger" and waiting for a few minutes, all the defunct processes died off and I was able to install/upgrade with zmlogger ON, and it seemed to have worked.
Looking forward to having logging again! Hopefully this time it won't get corrupted.
