Two problems (SuperDrive error with no disc; iMovie '08 hangs)

1) An error message randomly pops up telling me that the disc I inserted into the SuperDrive could not be read. The drive is empty when these messages appear.
2) iMovie '08 beachballs after recording/importing a video. Right after I click 'Stop' or whatever it says. When I reopen iMovie (after Force Quitting) it processes the video then.

Yes, I have tried the "one-size-fits-all" solution, Repairing Permissions. Two were repaired but, as in 99% of situations it didn't help or even fix anything related to the problem.

Can you help? If not, I'll cry!

 

Thanks for all the help, guys, you are all so awesome!