We seem to be experiencing this problem too. Occasionally after a reboot one of the ports disappears. We are not overclocking, nor is the PC doing anything "strenuous".

This is a serious problem for us, as the fitPC runs embedded inside a control panel and is not really accessible by a user to turn on or off. Also one of the ethernet ports is simply patched to the user's control panel which will allow them to connect as required, it is unlikely that there will be a permanent connection though and especially not during power-up/restarts. If the ports are disapperaing after a reboot, then it can make the whole system temporarily inaccessible to the user.

There seems to be an option in the bios that allow the two ethernet ports on the fit PC to be enabled as required, always on, or always off. These settings are at always on and don't seem to affect whether or not the ports dissapear.

Any help appreciated.
Thanks.

That's using pre-installed version of XP.

Please, provide us the Ethernet driver's version.