[NTLK] new problem baking up and exporting

[Dr. James Charney]

Hi--I have a 2100 that I routinely back up to my old Mac Powerbook running Classic .  This has always worked well and smoothly.  But suddenly there is a problem.  My Newton connects OK with NCU on my Mac.  I tap Backup and it prepares for backup (barber pole turns)--but then it disconnects and gives an uninformative Error Report (#1).  this also happens if I try to Export, say, Names.  It begins fine, then abruptly disconnects before actually exporting anything.  Same error message. 
	 I've tried Restarts of both the Newton and the Powerbook--but the problem persists.
	Any idea what's wrong---and how to fix it?
James