>Have you ever, by misteak ofcourse, left the cover down, w/o paper in the printer, then pressed the "PRINT" BOTTON? The paper comes out black.
This will happen only if the bottom of the copier's cover is black. Most aren't. There are good reasons to make them black, but they only apply when making certain types of copies. For example, if you're copying a document with text or graphics on both sides, having the cover dark will help prevent "ghosts" of the reverse side showing up on the copy.
It would be a good idea to clean the glass on the copier before you start. It gets all sorts of crap on it.
I used to work at a copy shop, so I've cleaned lots of copier glass!
Qapla'
SSB