I'm relatively new to Ubuntu. I've looked around for problems like mine, but haven't really found one. It's been sort of an evolving process.
First thing that happened is that I could not use Firefox. Later, other programs would not work. I can't run Software Center and a few other programs. Now, I have a red circle in the top right hand corner that says "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:Read error - read (5: Input/output error), E:The package lists or status file could not be parsed or opened.)'This usually means that your installed packages have unmet dependencies"
When I run Synaptic Package Manager, it loads for a while, then displays an error box that says a similar thing to this. When I try apt-get in Terminal, it says it can't do something because of a lock open file. "13: Permission denied"
Thanks if someone knows about this