Weird error message in Cocoa Emacs

[Emanuel Evans]

I keep getting a weird error message at seemingly random times: 

>"Error in process sentinal: Wrong argument type: window-live-p, nil"

Emacs will temporarily freeze up when it gives the error message but usually
only for a second or two.  Sometimes, the error is given repeatedly for a few
seconds and I can hear disk activity.  I can't figure out any pattern
and I have no idea what could be causing it--maybe a system process of
some sort?  I'm using Cocoa Emacs 23.3 on Snow Leopard.  Does anyone
have any idea what might be causing this?