In Start button\type; services.msc [hit enter]\look for
Plug and Play service and check if it's running. next
uninstall the modem in the Device Manager and restart
your computer.... wait a few minutes to allow Windows
to auto-install your modem.
If it does not auto-install, go to the Device manager and
click right on the computer name and click on search for
new hardware.   That will probably auto-install it with the
Windows driver[s] which are most compatable.
If that still doesn't install the modem, try the following link.

How To Configure Devices By Using Device Manager in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;en-us;307970
This step-by-step article describes how you can configure devices by
using Device Manager in Windows XP. When you install a Plug and
Play device, Windows automatically configures the device so it will work
properly with the other devices that are installed on your computer...

Saludos.

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