server drops off network when logon screen appears
 

I have a server that when I restart it and it brings up eth0 I can ping it, but the second the logon screen comes up it drops from the network. Its a dell poweredge 2950.
Even if I log on and do a ifconfig eth0 up it still doesn't respond to the pings

Maybe during startup eth0 and eth1 were disabled resp. enabled - is there more than one network card? The numbering during the boot process (i.e. like used for PXE) may not be the same lateron when the OS is up. This can be changed in /etc/udev/rules.d (or alike in your particular distribution).

I'm not sure what happened. After i did a /etc/init.d/network restart though it stayed back up. Very concerning though, in the event i ever have to restart this remotely.