Running Debian Unstable. Recently when booting I sometimes get the message:

eth0: link down

and then the PC cannot connect to the network. There are 5 DHCP DISCOVER attempts and then it gives up. Once booted, ifup eth0 doesn't work.

This NEVER happens if I boot Mandrake 10.1 and in fact booting Mandrake and the restarting and choosing Debian seems to fix it.

The problem _might_ be related too an init tools upgrade. Not sure.

Can anybody suggest a way to proceed to fix this?

Do you have multiple enabled network controllers on that computer?

As I have noticed on my computers running Debian testing/unstable that have multiple enabled network controllers that on some bootups the NICs get reordered, so e.g. the network controller that is normally eth0 becomes eth1, so the "new" eth0 doesn't have any cable connected to it (as it is connected to the "new" eth1) and thus it fails to acquire an address.
A solution would be to disable the network controllers one doesn't use, e.g. for onboard network controllers there is typically some setting in the BIOS that allows one to do so.

Thanks, that may have done the trick. I disabled the on-board NIC, which is there as a "spare" and rebooted twice successfully.

I can confirm that that was the solution. I rebooted about 5 times today (no, not problems, switching OSes) and each time the PC booted OK as far as this went. (there's another new problem but that's for another question if it persists)

Thanks dastrike.