My piece of crap does it too. (I hope I don't have to KEEP this too long !)
I adjusted all the mic settings to workable levels, but the harmonizer is still buggin'.

BTW - looks like that Tyros deal is gonna fly. I must be nuts, but I can't overlook the finacial plusses of this deal. The PA80 will probably go on Sunday afternoon. That means i HAVE to play this 2100 for a while. Yuk. At least I have that one night on a real piano to distract me.

I'll fiddle with the mic settings and see if I can narrow the glitch down.
sigh.