I'm sorry to hear that you're having this issue.
I'd recommend having the unit serviced my a technician. Unfortunately, I can't diagnose what's wrong based on the description alone, but a qualified technician would be able to give you a better idea of what's wrong, and what would fix the unit.
I have the Samsung LN32A450 LCD tv and after a year and a half the picture displays as opaque white. You can see images, but they are very faint. Has anyone else experienced this and what did you do about it?