Hi, My iMac will no longer play DVDs. CDs still work fine, and when I insert a DVD it seems to accept it mechanically, but no icon shows up on the desktop. I'm pretty sure the problem was the result of my downloading a video app which (I discovered too late) was only compatible with OS10.4 and higher. I deleted it, naturally, but I fear it corrupted or overwrote my DVD software. Could one of you good folk out there suggest an idiot-proof way I might repair or restore my DVD software? Many Thanks!