I am having the same problem after having it for 4 years and i cant afford to send it to nintendo for repairs. I have been told that this is a common problem with the laser and that with me turning the power off while i have a disc in especially playing it the laser will stop where it is instead of going back to the position it should be in so when you put a game in to play later the laser starts in the wrong place effectively making it jam. I have now put mine lying down and putting the disc in then when it says there is an error i do as it say's, up to now it is loading more each time i try it so with fingers crossed it will work.
D. Greenwood, March 2011