I know this is an old thread, but I thought I would just put in my 2 cents. =)
About a year ago I got the same error and cleaned the disk and it seemed to work just fine on my ride home. Later that night, I went to the store and it spit the CD out and would not work at all. I just ignored the issue and put it on radio. The next morning my battery was dead. Once I got it jumped, I noticed that the eject motor was running even with no CD. So I pulled the fuse to save my battery while at work. I tried all of the suggested methods above with no luck. I then decided it was more worth my time to get a new head unit. I'm so glad I did. I love the look on peoples faces when they get in and say, "Dang, you put a TV in a Malibu?" Priceless!