Ubuntu Installation :: Latest Update Affects Shutdown And Volume

There's some bug or other error in the updates I've just installed. I run Update Manager very frequently (almost daily). The last time I ran it was 2 days ago, so this bug can only have been released into updates today or yesterday. I ran it this evening and there were quite a lot of new updates (around 50mb in total), and I installed them all without really checking to see what they were - but as I'm new to Linux I don't exactly have any weird or rare software running on my laptop, so they only would have been for Ubuntu itself or some very common programs.

After installing it required a reboot. Upon booting up again, the volume icon has turned to 'Mute All' and I am unable to turn my laptop off. Telling it to shut down simply causes the screen to go black for a couple of seconds and then return to the login screen. I also notice that the Suspend/Hibernate options have disappeared, and I now only have the option to Log Out, Restart or Shut Down. {As I'm new to Linux I have no idea how best to proceed, or even how to officially 'report' this if indeed it is a bug contained in one of the updates.}