If you have this error “The disk drive for /tmp is not ready or not present” it is related to mountall utility bug which tries to mount the temp folder before it has been cleared of leftovers from previous boot.
That explains the inconsistency of the error: you only get it when there is really a lot of files left in the temp folder from previous run. In the recent mountal versions the bug is fixed, however it is only available for the short-lived Ubuntu 13, while long-time suport Ubuntu 12 doesn’t fetch the update. So to at least somehow fix the issue, add this command to your fstab to mount tmp to ram drive.