zillions of mgetty.log.ttyS4.1.1.1.1... messages

[Billy Davis]

We have a RH7.3 server with an internal modem set up as ttyS4.  The modem works great whenever we need to dial in or out.  However, yesterday, the Server started acting very strangely (spooler quit printing, modem would not answer the phone) and we started getting an error message about 'mgetty trying to respawn to quickly, port locked for 5 minutes'.  While trying to find out what was going on, I happened to notice that there were a 'zillion'  zero byte length messages in /var/log named mgetty.log.ttyS4.1.1.1.1... up thru mgetty.log.ttyS4.4.4.4.4.4...  It took 30 minutes to delete them all (they could not be deleted with a single rm command), but after they were deleted, the system started acting normally again.  Does anybody know what caused this problem and how to prevent it from occurring again?   Thanks, Billy