3comm 905nic going offline !

Win2000 pro with a 3comm nic card. It keeps going on and offline. I checked power settings (power saving devices also) thinking this may be it but they are all OK.
I have never run across this before. I even replaced tyhe nic but the same thing happens. Again, I checked all power and power saving settings in Windows and the BIOS. Everything is turned off and OK.

Thanks
Merv