I just experienced a very strange error on my Bonobo bonp5. Executive summary: the / filesystem apparently spontaneously unmounted while the system was running. Upon reboot, everything appears normal, but... I'm worried.
I had Unity running with a terminal, a GIMP session, and Chrome open in different workspaces. Suddenly, the launcher and all status icons disappeared, although I could still switch between workspaces and my apps continued to run with no apparent problems.
However, when I switched to the terminal and did "sudo service network-manager status" (because the first thing I consciously noticed was the absence of the network-manager status icon), I got:
sudo: command not found
ls: command not found
Buh wuh huh how?
mount: command not found
So... it appears my root filesystem is suddenly just GONE?
At this point I tried to save the image I had open in GIMP, and that apparently succeeded. (Upon reboot I re-opened the image, and it was in fact saved.) Then I thought long and hard about whether to reboot, or try to copy some important data off of machine before rebooting. Then I realized that it would probably not be possible to even mount an external disk, since /bin and /usr/bin were both apparently MIA, and if need be I could pull the internal disk and copy important stuff. So I took the plunge and powered off the machine. ("sync" and "shutdown -h" both resulted in "command not found" - I was hoping "sync" might be a bash internal, but apparently not.)
Luckily, the it rebooted successfully, and I'm using it now to post this message. But I have NEVER seen this kind of utterly weird behavior from a Linux machine before except in cases of incipient catastrophic hardware failure. The root filesystem is on a 120GB SSD, and all the important stuff is on a 750GB spinning disk.
Has anyone ever seen anything like this?