10 Mbps instead of 100 Mbps

I am the Tech Coordinator for an elementary school. I have one computer out of 130 that is showing its network connection at 10 Mbps instead of 100 Mbps that all the others are connecting at. The drop line from the server connects to a hub that provides service to a desktop and a laptop. The NIC is a Realtek 8139 and when I try to configure it to connect at 100, I get the "network cable is uplugged" error, although it does show the 10 half, 10 full, 100 half, 100 full-duplex as options, which makes me think the card is ok. Any suggestions as to how I might troubleshoot?

 

Possible bad cable or port. Try another Cable, or even plug into another port