Quote Originally Posted by Getnikar
Am I correct that this proves that the cd is burnt correctly, and a true image of the distro?
I don't know that there is any proof. The problem seem to be that there is a lot of error recovery data on a CD and the error recovery process can hide the occasional read error (as it is intended to do). But the error recovery process just doesn't seem to help at boot time. So we have repeatedly seen that disks burnt at high speed fail to boot in strange ways or, when they do boot, they boot much slower than they should. This happens even if the disc image has passed an MD5 test or was checked with the "verify image" option in Nero. See this thread and this one and this one for just a few examples.

So when people are fighting problems that sound like the high speed burn issues we have seen in the past, it's a pretty reasonable thing for us to suggest that they do their burns at low speed, it eliminates a potential contribution to boot problems that we have seen all too often.