I'll tell you the whole story.
I decided to upgrade my natty from alpha to beta after a long time.After the updates has been downloaded, the system crashed during installation. I rebooted the system and during the plymouth screen I greeted with the error message
"Disk Drive / not ready yet or not available"
and options to wait,skip or manually recover
If I choose to skip, it gives the same error,but with /tmp this time.
And if I skip again, it just freezes.
If I choose the option to manually recover, I get a maintenance shell.