Adding an IDE hard drive

The server I inherited has two (2) 9 Gb SCSI hard drives. I am trying to add an 80 Gb IDE hard drive just for storage. When I connect the IDE drive the server pases the POST tests and hangs at the next screen. Without the IDE drive it boots fine. The bios shows that it should support this drive by the date and version numbers per the manufacturers web site. Is the server looking at the IDE drive as if it is the Boot drive? If so how do I get around this?