Last night I tried to upgrade from Ubuntu 11.10 to 12.04. The upgrade process had numerous errors, but I let it continue assuming that it would safer than interrupting it. Near the end, two conflicting messages appeared: "too many errors" and there was also a message telling me that the system was upgraded nonetheless. The only option I was presented at that point was to reboot, which I did, but the reboot just hanged. Then I tried to boot under "recovery mode" but the system gets into an infinite loop with the message
/lib/recovery-mode/recovery-menu: line 109: /lib/recovery-mode/options/whiptail: No such file.
I am at a loss. Any help is greatly appreciated. Thanks.