On three occasions in the past two weeks I have started up my new Lowrance 500c at times between 11:00 and 1:00, and have been unable to see anything on the screen at normal viewing distance. If I get real close I can barely make out that the icons and map are on the screen. The view does not get any brighter if I hold up a hand to block the sunlight. I can't tell if this is a defect of the unit I have, or if this has something to do with total ambient light. Anyone else experience this with any GPS, and, if so, did you find a fix? Thanks.