I recently rebooted my Debian desktop, and there is no working network now.  Networking has "just worked" for so long that I am at a loss as to what to do.

I haven't changed /etc/network/interfaces in forever, but ifconfig -a shows that eth0 is not being configured, and if down eth0 confirms it.

I tried fiddling with the Network Tools thing in Gnome, but it hasn't changed anything.  Did I miss a change to how this is done and need to learn a new approach?

Thanks!