My dvd rewriter in the computer was doing this last week. Saying either no disc in or no room on disc when it was a blank disc. I got upside its head and gave it a good slap. It's now broken and will never mess with me again. I have a stand alone dvdr connected to the tv setup and a stand alone cdr connected to the hifi so I can break computer related ones with impunity.

i've got memorex cd-r and they're alright. cd-rw will not necessarily play on cd players. they only play if the stereo has a built in mp3 player or something....
are you sure it's not burning? and that it's not just that the cd player won't play it? did you let it finish.
basically, it you're trying to do mix tapes, you want cd-r rather than rw (rewritable) as there's not really any point in rewriting them and they won't play. this would also explain the 'no disk' thing. just get new cds. memorex or sony are good.