Burning smell in Disc Drive & on disc

HELP!!!! Every time I burn a disc a burning electrical smell comes from the drive. It does sound like it is making more noise then usual. When the disc is ready it smells very strongly aswell. Please help as I need to burn quite a few more over the next week or two. I am scared the imac hard drive will die. I have a imac OSX and is 4 years old.

Regards Azzie