I've found that USB devices can be very very VERY flaky in terms of your system's ability to boot up; we recently found that out with an external USB hard drive, which would prevent the system from booting at all. I'm not exactly sure why this it, but if the problem doesn't go away when you switch the USB connector to a different USB port, my suggestion would be to sink $20 into an internal network card, if your system can handle it, and ask your cable co to swap the USB modem for an Ethernet version.
― Sean Carruthers (SeanC), Monday, 10 March 2003 17:53 (twenty-three years ago)