Hi I have recently been experiencing some minor (I think...) problems with my MacBook Pro (15" Early 2011). Sometimes when I switch it on it comes up with the usual white screen, and then turns itself off again. Then once I switch it on again it comes up with a funny looking, discoloured screen covered with lines and is sometimes out of proportion (like half the usual image taking up the whole screen). , I have also noticed that since installing Lion (which I did months ago when it first came out) the speed of it booting up was a lot slower. It used to boot in about 25 seconds, but it's now it takes just over a minute. I have everything backed up on my external hard-drive through Time Machine, so can I restore the operating system and put everything back on? Would that make a difference? If so can you please give me instructions on how to do so? Or, would it be better to take it to an Apple Store? Thanks, Taylor.