And this time it's straight from Active Voice Support:
M150-1 errors are Voicemail database corruption errors. These usually result from either a "dirty shutdown" (power failure, or other pc shutdown without first stopping voicemail), or from hard disk crashes. Given your other reported problems, I suspect the hard disk is dying.
The Active Voice Repartee voicemail system was originally built about 10 years ago and runs on OS/2 Warp. It’s one of the most stable and robust voicemail system ever built.
That being said, things do go wrong. On a system that I was working on the other day, we had a great problem with the database. Whenever the system started, we were prompted with a number of database errors.