Computer Drops ADSL Connection When Printing

> Hi,
> I have an ADSL connection on a dial up through a USB ADSL modem. This
> works
> fine until I try printing, as soon as the print job is sent the ADSL
> connection is lost and cannot be re-connected unless I restart the
> machine.
> Also the printing is either very slow or stops half way through. If I
> unplug
> the modem the printer works fine and if I unplug the printer the ADSL
> connection is fine. The machine is stand alone and not networked in any
> way.
> Does anyone have any ideas as to how to cure this annoying problem!
> Thanks
> Rob