I suddenly began having the power calibration error and since my burner is going on 8 years old I decided it was time for a new one anyway. I bought a Sony external burner and was getting the same power calibration error. I was looking around in the Control Panel and found the Nero Imagedrive Icon and opened that and apparently it had become disabled. I enabled it and now both drives are burning fine.

Yes it seems this error usually is because of the type of DvD or Cd you use I had same problem. So whenever you get this error I would strongly suggest you first try a new BRAND on DVD, CD before trying anything else since that might solve your problem. If this doesn't solve it then you should start reading about other possibilities(nero might be out of date, Laser might be filled with dust etc...)