My PS2 Slims is acting all screwy.?

I have a black PS2 Slim and a silver PS2 Slim, and they both are acting up, to the point steam is shooting out of my ears. My black one acts REAL picky on which DVDs it'll play. My silver one leaves a burn ring on any disc that I put in. What both of them have in common is when I'm playing a DVD, the controls act on their own accord, without me messing with them. If I take the controller out, it's fine, but it's pissing me off royally. Any help?