I am using Illustrator CS5 and the grey background around the outside of my canvas/page I used to have and loved has gone white. I do not know why. I can not change the colour in preferences-user interface, as this was introduced in CS6. I have tried ticking and unticking the overprint preview and this makes no difference. Any help would be much appreciated.
View > Overprint Preview
Turn that off if you want to see the tinted pasteboard around artboards.
It could also be
Hide Artboards as @TimesWasting suggests