Dell computer's cd-rom unit accepted disk, then made a 'pffttzz' sound and a big puff of smoke, game in pieces

I did an internet search on the problem, could it be dust or sometning else? the unit is about 2 years old. of course out of warrenty. the whole back of computer WAS covered with fine clumped dust. We got most of the many pieces out, not all.

It basically 'exploded'. The circular disk inside the unit, that CAUSES the cd/game to spin is usually 'invisible' but now youcan see all of it. There are a few fragments of disk inside. We finally got it to close, but it automatically opens again. We were using this computer and cd drive as we normally do, nothing was dropped, spilled, etc. My brilliant 15 yr old figured how to remove the unit. 1)Should we get it fixed. 2) can it be replaced with any other DELL cd/rom unit from an older (in the cellar no longer used) computer, are these units availible for stand-alone purchase or should I just get a whole new computer (and can you just get the CPU? the moniter speakers etc are just great.sons get new cd games for XMASS BUT NO CD/Rom now!