Lines and circles across all of my pictures

Question

I have had the Fuji FinePix E550 for around 8 months and I have had no problems with it until recently. Whenever I take a picture it looks great on the display but when I view it in playback mode or on the computer lines appear across the whole picture. The best way to descibe them (as I can't post a picture here) is that they resemble wood grain, and eminate in many ellipses from the centre of the picture. This is very frustrating as it has already ruined numerous photo's, and I wpould like to try and get it sorted without sending it back to the manufacturer.