Samsung Drive Issues

My drive is no longer recognizing disks in the tray. It's a Samsung SDG-605B. The drive opens and closes with no issues, I can hear the laser rack moving back and forth (or I believe that is what it is). But the disk looks like it hasn't moved. WHat is the sequence of events after the tray closes? Shouldn't the disk spin and then the laser searches for the beginning? I replaced the laser about a year ago and have had no troubles since then. As a matter of fact two days ago I watched a movie and had no problems. Then yesterday I popped a new game in (new to me) to burn it onto the HD and nothing. I tried every game I own and I get the no disk display on my dashboard. Any suggestions are greatly appreciated.