Serial Console Problem

Not sure if this is quite on topic for linux-kernel but I couldn't find answers anywhere else so here goes:

I've got a couple systems where I've configured ttyS0 as a serial console. Everything works fine when a cable is plugged in and a terminal is listening on the other side. The kernel in question is 2.4.20.

However, unplugging the cable and rebooting results in the boot process hanging. It appears that the kernel is waiting for the serial port acknoledge the fact that it is writing data.

What's strange is that this is a problem on one machine, but doesn't appear to be a problem on another.

Anyone have any ideas on how to work around this issue besides leaving a terminal hooked up all the time?

-Dave