The Microsoft IIS (Internet Information Services), listen by default on port 80/TCP and on some version of Microsoft Windows like Windows Embedded Standard 7, it's installed as default.
This system service so became in conflict with the default listening service of JMobile PC Runtime.
This FAQ explains how to disable the IIS in a Windows Embedded 7 environment to allow the JMobile PC Runtime software to listening on default port 80/tcp.
Anyway, if JMobile PC Runtime found port 80/tcp already occupied, it asks to change listening port into one available.
Windows OS