On starting up my PC, white dashes appear on the screen behind the system info etc. When the Windows logo appears, there are lines of blue dashes vertically and horizontally on the page (the position of these dashes changes each time I switch on) When the desktop appears, the icons have rows of small black dashes around them, as does the cursor. The applications themselves appear to work ok with no display abnormalities. The PC seems to be working ok apart from these strange dashes - I've checked the forum history but can't find any similar situations to mine. Any ideas?