Software :: Unable To Work With CD Burner / Won't Write

I have Mac OS X 10.4.11. with an internal Pioneer DVR-106D CD/DVD burner. I "capture" opera performances on-line, edit them with CD Spin Doctor 2, send it to Toast where it is then burned to disc. I have been doing this for years with no problems. This past week I started receiving the following message "sense key=medium error. Sense code= OX73, OX03". I tried several different CDs and had three different brands which always did work but stopped working...Philips CD-R, TDK, Memorex Black CD-R. I had two Maxell CD-Rs and they worked. I purchased a cleaning disc hoping that cleaning the lens would correct the problem. Still none of the previously mentioned CD-Rs would work and I was unable to purchase additional Maxell discs locally. At Sam's Club I purchased Verbatim CD-R, placed one in the computer.....and it worked. For almost a week I've been able to burn CDs once more, until tonight. Again, I used the cleaner disc plus retried some of the other brands of CD with the same results...no burn. When I tried burning a disc with iTunes, I received the following message "The attempt to burn a disc failed. The device failed to calibate the laser power level for this media."