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?

>>also modems don't freeze, they reboot themselves

The lights don't "stay the same" - the PC activity light stops flashing and just... glows eerily. And the only way to get the connection back is to power cycle the modem (since it doesn't have a restart button and won't let me into its config interface). Also, I can't get an ethernet card, because the machine already has one - it is used for a home network to share the modem's connection so that I can get internet access on MY machine and post this little piece of text. So there you have it.