I have a Dell 24" TFT monitor which I purchased with my system, I have noticed, occasionally, blue flickering horizontal lines on the right hand side of the screen wich reach about 10 inches across the screen to the left. If I power off the monitor and power it back on the lines dissapear. There does not seem to be any pattern to the lines appearing, the only USB device I have plugged into the monitor is a Logitech MX518 mouse. Should I be concerned? Cheers,