The "Start" button often gets corrupted, usually after a long period of running with coloured pixcels which sometimes resemble the colours of a background scxreen. Sometimes when I click on Start the veretical column of the left of the pop up menu is similiarly corrupted. These two symptoms are not necessarily present at th esame time but they can be. I think th eproblem started when I fitted a Geforce graphics card and ran "Easyfly". My system tends to crash about once per day; I run McAfee Viruscan all the time.