As reported I can't get an Internet connection with my Davicon eth card unless I boot in "cli" mode.
That is the strangest thing I've heard in a long time.
Now here is a new twist:
If I boot "cli vga=791" again I cannot connect to the Internet.
Ditto. If I were a betting man it would seem to me to some sort of weird PCI BIOS conflict between the ethernet card and your video card. But maybe I'm way off the planet here
If I were you I would go into your BIOS setup, reset it to its default values, then reset the time and anything else that needs doing, but leave everything else, and then reboot and try again. Also, show us the output to these commands when it works and when it doesn't work:
dmesg | grep eth0