Which version of Mac OS X are you running on?
Are you running a desktop server (from the application) or a system server (running in the background)?
Usually screen registration only needs to occur when the server first starts up, are you doing anything that might be requiring it to re-register (changing screen resolution, using Fast User Switching, etc?)
I’m running this on Mac OS X 10.4.11 with the desktop server. No changing of screen resolutions or user switching happens at the time the viewer connects.
I do run a dual display setup and when the viewer does connect for just a minute or so, it grabs the first display.
The error shows up after enabling dynamic desktop sizing for the client and the subsequent client connected status message saying ‘Registering Screen Update Notification’, which almost immediately produces the error in the log.
Then about 11 seconds later I get a rfbSendUpdateBuf: write: Broken pipe with an operation time out error and a subsequent disconnect.