Cable modem keeps freezing up

I have a Motorola SB5101 cable modem connected via USB to a machine for internet access. Problem is, the stupid modem keeps freezing up. It started after three months, first once or twice a week, but eventually it grew more frequent, to the point that in the last 7 hours it happened five times. A google search turned up that this particular model doesn't get along with USB, but there is no way for me to connect it via an ethernet cable. Any suggestions?

Okay, I bought another ethernet card (OEM), put it in the machine and windows failed to recognize it. When I tried installing the driver manually, the system hung up and now hangs up on windows startup whenever the card is inserted.