Thank you for your instant response.
I do not think this is a resource conflict, as the soundcard is not and no drivers are loaded. I changed the IO Port settings and the IRQ but with no success.
Meanwhile I looked (as you suggested) at the messages from the time when the card was working. And it looks like there might be something usefull.
In times when the card was working it told
eth0: Digital DS21143 Tulip rev 65 at 0x200, 00:80:C8:8F:61:0C, IRQ 5. eth0: EEPROM default media type Autosense. eth0: Index #0 - Media MII (#11) described by a 21142 MII PHY (3) block. eth0: MII transceiver #0 config 3000 status 7809 advertising 01e1.
In contrary to when it is not working: (Note the changed port and IRQ due to the modification of config.opt you suggested)
eth0: Digital DS21143 Tulip rev 73 at 0x400, 00:80:00:80:00:80, IRQ 9. eth0: EEPROM default media type 10baseT. eth0: MII transceiver #0 config 3000 status 7809 advertising 01e1
It looks like he think there is another Chipset revision present now, and he is not even able to read the MAC address.
A DOS diagnosis tool read the following MAC configuration
Node ID 00 80 C8 8F 61 0C I/O Base Address 500 Interrupt Number 11
Is this of any help to you or anybody who knows something about?