Computer stays awake when shut (and sleeps when open)
I have always had my MacBook Pro (13-inch, 2010 model) automatically sleep when I close the lid, and then wake up when I open it again. A few weeks ago, my screen started going off suddenly (as if asleep) randomly during normal use of the computer. It could be as simple as browsing, or more complicated things like video or photo editing (although these problems were more rare). I thought little of it, until a few days ago, when the opposite started happening. I noticed the Apple logo would illuminate after I had shut the lid. After shutting the lid, it would first dim, as normal, but then come back on a few seconds later. I had to reopen and close it a number of times before it would sleep.
I've tried Googling responses, but all the results came up as people trying to turn off the feature where their Mac sleeps when the lid is closed, which I don't want to do.
This may or may not be related, but in the centre of my screen there has been for a while now what appears to be a darker spot (for lack of a better description. Possibly due to pressure against the screen or something similar.
MacBook Pro, Mac OS X (10.6.8)