PS3 won't recognize some DVDs

[Zen_Amako]

A couple of months ago, my original 60GB PS3 got the YLOD so I bought a new slim. Since I got the slim, I've mainly played BDs and games on it.

Yesterday, I tried to play a DVD and the PS3 wouldn't recognize the disc. After the DVD was inserted, it tried to read it, but then it made an "eject" sound and sat there with the disc still inside. The "DVD-Video" never appeared on the XMB. I then tried several other DVDs, and some worked fine, while others didn't. I put in my copy of Heavy Metal (the animated movie) and that played fine. However, when I tried one of Sony's Godzilla DVDs, the PS3 did the same thing and would not recognize the DVD.

Does anyone know why a PS3 slim would play some DVDs without a hitch and not even recognize others? The DVDs it wouldn't read play fine in my other player. I tried searching around to see if anybody else had this problem but I didn't find anything except people who couldn't play DVDs at all.

I'm a little frustrated because this PS3 is only a couple of months old. I could probably return it, but then I'd have to download all my PS Store content *again*. So hopefully I'm just overlooking something.

Some DVDs it would not play: Ong Bak 2, Godzilla Vs. Hedorah, Captain Herlock (anime)
Some DVDs it played fine: Heavy Metal, Mulholland Dr., Hard Boiled

All of the DVDs I have tried are region 1.