When you do that sho int, does it say the both Ethernet0 is up and the line protocol as well? from inside your CLI, can you ping the outside world? Are you using a static IP for the eth0 interface? if so did you set the static route up as well. Since the PIX rebooted and it was working before, are you sure you had saved the running-config to the startup-config before you exited the CLI previously. If not the reboot will have taken you back to your last saved startup-config.
One thing I always do is copy my config lines to a notepad or word document so that I can compare what I know worked with what is on running-config.
Just some things to check :)
Dave