Unable to install Zoltrix modem

I have a Zoltrix 56Kpci modem, called the phantom which I can't get NT to detect. I have the correct drivers for the modem and think this is a problem with my com ports. When I boot up I get a message in Event Viewer that says "while validating that com3 was a seriall port the contents of the divisor latch register was identical to the interrupt enable & receive registers. The device is assumed not to be a serial port & will be deleted." What does this mean. I am running NT 4.0 which was installed off of BackOffice CD ver 2.5 (I think). What does this message mean and how do I fix