Probably one of the easiest things to do is to delete the modem or it may simple communications device from device manager. Then look in add and remove programs for any reference to the modem, if there is any uninstall it.
If you now reboot windows should see it and assign a virtual port for it. Usually comm3 or comm4. You will then have to reinstall the drivers. Then everything should work.
The other thing that may be at fault is that comm2 is disabled in the bios.
Your first port of call should be a look in the bios.
restart the machine and keep pressing delete. This should bring you to the bios \ cmos. Look for a main or sub heading of IRQ activities. Comm 2 should be on IRQ3. If it is disabled, change it to enabled by using the PgUp button. Press esc, then save settings and exit with a y.
I have done all the above but still getting nowhere. The modem is now on COM2 which has been enabled on the BIOS. The port settings seem to be correct according to the manual but still I get the following message when trying to dial out: 'No modem indentified blah, blah' The modem is recognised on Device Manager and everywhere else. When run the diagnostic and ask for more info on the moden I get this ' cannot read port name from registry' then I get the info for the port. Modem type: OPine 56K PCI V.90 with Conexant Chipset PCI HSF