Only had my monitor plugged in at the time and a network cable.Sounds like a driver or hardware problem somewhere. This can happen with things that are plugged into it.
Superb! will take a look at that later on, could well be the problem. Was going to try a 'repair permissions' first so good to see it noted in there.http://www.wired.com/gadgetlab/2013/10/mavericks-issues-and-fixes/?viewall=true
I've used the fix for stalled/slow shutdowns on this link on a number of machines and it has fixed it every time.