IWP Port setup errors

[RDWirr]

I have a FM 10 Pro Advanced DB that I am trying to publish on a company intranet. There is no FM server program running on the network. I have been trying to test this set up from the computer that the DB was developed on. This is a WinXP-SP3 machine. When I try to switch on IWP I get the message saying there is a port conflict on port 80. When I try to change it to any others (including 591) I get the same message that there is a Port conflict. I have tried many ports up to the max and still this problem. I have also turned off the Firewall and Virus protection but still no success.

Thanks in advance for any help.

RDW