Weird Modem problem

Any help would be appreciated. I have a system where the modem connects at 48Kbs or so but all the download speeds seem to be limited to 31Kbs. I have tried different dial up methods, swapped modems and nothing seems to help. I check out the connection on other machines and nothing is wrong. The only thing different is this is Win 2000, fully updated.

Any ideas what is choking my throughput?

Thanks guys.

What kind of speed do you get when using other machines? And what is the difference between your machine and the others?

Other machines on the same line get 48Kbs with downloads. Only the Win 2000 machine has a problem. The other machines are an AMD 4200+ and an Intel Celeron 2.4. Nothing I am aware of in hardware can slow the modem throughput other than the modem, the software, and the landline so I don’t think it is hardware.

The problem machine is just an AMD Semperon 2800+ so it is between the other two machines in speed.