Sorry to hear that. Would see if you can get a Modem that attaches to a LAN card (or slot) on your computer. Personal recommendation "do not use a USB modem"!!!
Other than that spend $20 or so dollars on an add on USB card w/ a NEC chipset. Check out AOL forums w/ people w same problems. Go to
www.usbman.com to see if they have any answers.
Buy a compatable modem on e-bay. That's what I recommended (and did) for a coworker who was having all sorts of problems w/
her SBC Broadband connection. She's never been happier. Saved her from switching to Cable. She claims her computer is even faster. Who knows? High speed internet good, USB modem BAD!!! Good luck (BTW she runs Win98SE)