Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!att!chinet!mcdchg!ddsw1!ddsw1!vpnet!lisbon
From: lisbon@vpnet.UUCP (Gerry Swetsky)
Newsgroups: comp.unix.i386
Subject: serial ports under 2.0.x
Keywords: serial
Message-ID: <[25274c50:303.1]comp.unix.i386;1@vpnet.UUCP>
Date: 2 Oct 89 14:00:04 GMT
References: <183@trwrb.UUCP>
Lines: 7

Sounds as if you're experiencing an interrupt conflict on your serial
port.  Similiar thing happened at vpnet.  Check /etc/conf/cf.d/asy.  If
another device is using either interrupt three or four there is a way
to open only ONE of the two serial ports and thus free up the interrupt
in conflict.

I'd write more, but I gotta get to work.  Mail me for more info.