Below I've pasted a snippet of my desktop where the squares appeared to day. Yesterday they appeared different places in Mail. The squares are about 14 x 14 pixels I guess it's a graphics related issue but how bad do you think it is? And has anyone had similar experiences? I've tried Google but didn't find anything. My computer: MBA 2011 i7 4GB, 256GB, about 3 months old but only used for two of them due to travelling.