I was working when I noticed a red icon on the top panel. I clicked on it and got this message:
An error occurred, please run package manager from the right-click menu or apt-get in a terminal to see what is wrong. The error message was: 'Error: Opening the cache (E:Couldn't create a temporary file to work with /var/lib/apt/lists us.archive.ubuntu.com_ubuntu_dists_Vivid_Release - mkstemp (30: read-only file system) E:The package lists or status file could not be parsed or opened.)'. This usually means that your installed packages have unmet dependancies.
Since it will not let me open the terminal, Caja, or anything, I'm going to restart and see what happens.
Any ideas? I'm running Ubuntu MATE 15.04 Beta 1 64-bit.
Here is a picture of the error message. Sorry for the crappy camera.