my Ethernet is capped at 100 Mbps and Im losing my mind.

USB Audio Device Properties
Device status:
This device cannot start. (Code 10)
{Operation Failed}
The requested operation was unsuccessful.
the home-built tower is plugged into a gigabit switch setup. the adapter details say 100 Mbps full duplex :D my laptop on teh same cable and port negotiates gigabit just fine, sooo teh switch port seems okay. the only change on the home-built tower was the PCIe Gigabit Ethernet 10/100/1000M Controller Driver update from Realtek. what settings should I look at?