MacBook Pro CD burning is not permanent I am trying to burn a bootable CD to update my harddisk firmware. This is what I have tried:

Using Disk Utility: pressing burn, selecting the bootable image, speed = maximum possible (24x), verify burned data is checked, pressing burn.
The superdrive spins, makes noises indicating that it's doing something, I get a message "burn succesful", and then the CD is mounted on the Desktop with all the expected contents. I eject the disc, insert it again and it's empty.

Again using Disk Utility: pressing burn, selecting the bootable image, speed = 8x, verify burned data is checked, pressing burn.
The superdrive spins, makes noises indicating that it's doing something, I get a message "burn succesful",  and then the CD is mounted on the Desktop with all the expected contents. I eject the disc, insert it again and it's empty.

Using the open source Burn app: going to Copy tab, dragging iso image in, pressing burn, verify data is checked, speed = 24x.
I get a message that all went well, the CD is mounted on the desktop, all contents are there, but on ejecting and inserting the disc again the disc shows as empty again.  

I tried this with 4 Philips discs.

Does anyone know what my problem could be? I'm on a MacBook Pro 5,3 with 10.6.8.
Looking around at different forums I found out that this behaviour might be caused by a dirty lens. I ended up buying this cleaning CD, and after giving it a spin I could burn CD's normally again.