Ran into this recently, though it might help someone else:
We have a Demo vSphere environment that gets banged around a lot, including getting shut down dirty often ("Look! I can yank the plug and it keeps running!"). One of our ESX hosts in the cluster came up with this fun error:
fsck.ext3: Unable to resolve 'UUID=####'
An error ocurred during the file system check. Dropping you to a shell; the system will reboot when you leave the shell.
The rest of the details in the message will tell you exactly which volume you've got issue with.
Usually, this is an easy enough fix; just force fsck.ext3 to clean your problem volume. I actually like to use it as an opportunity to check all my volumes. Here's what I do:
df --- get a list of all your volumes, they will as /dev/sdxx where xx is a hex number
fsck.ext3 -f /dev/sdxx ---- run this command on each volume on the df list
You'll have the problem volume prompt you about "Do you want to fix this?" "Do you want to fix that?" Just answer yes (after reviewing what you're about to do, of course), and you'll be good to go.
Reboot your host, and you should be up and running.
Here's some books that should help out:
Computer File Systems: Computer File, File Archiver, Fsck, 8.3 Filename, Root Directory, Working Directory, Comparison of File Systems
VMware vSphere 4 Administration Instant Reference
Mastering VMware vSphere 4 (Computer/Tech)