I rest my case with these pics:
A burned disc @52x tested on the Firewire case:
the same disc tested again:
So how a damaged sector can disappear and appear in another place?
the same disc tested with CD Quality Check:
When the same disc was tested again it shows errors in another part of the disc.
The final proof is that the burner is capable of 52x reading speed, I noticed that the led is flashing while reach the faster speed in these tests.
Now the same disc tested on drive connected on IDE port:
And now the CD Quality Check shows full speed:
My case came from a Creative 24x external drive, every time I bought a new drive I replaced the previous.
I have no writing problems, even read transfer test shows full speed but for testing with Scandisc or CD Quality Check errors appears.
What do you think?