Wow...today I got this error also! (I realize that this thread is REALLY REALLY old, but I generally don't like starting new ones for same issue)
Didn't add anything to the DB (other users may have?), and at the end of the service last week I tried to close ZW and when the DB index started...BAM!" Invalid Class Typecast".
I had to CTRL-ALT-DEL to close ZW.
Started it back up, unchecked the option to update text index when closing ZW, and the issue went away.
Then today I had to search by keyword cause the music team threw me a unplanned song, and "Invalid Class Typecast" error. And here's something even weirder...when that error occurred, the song list became invisible! The songs are still there, I can double click in the song list and it adds to the playlist...just cant see the titles!
I thought about this, could I "add" a new song now that I am getting this error? So I tried and found that I can add new songs. And when I did, the "visibility" of the song list returned.
I think the song list visibility thing is a glitch...the real problem is the "Invalid Class Typecast"
Any ideas?
Right now I cannot
1. update db index
2. search by keyword
-- worship is an active, deliberate, and rewarding act of love...just being there is not enough