ok, thanks for the tips both
* First I attached another HD. It gave the same error booting from cd.
* Then I took the suggestion to go to the bios and set to default. (that changed my first bootingdevice priority, so I put that back to cd)
but booting from cd still not work...
* In the meantime I downloaded the netinstall but the same frustrating result when trying to boot it.
This is sooo weird
I wonder if it could have maybe anything to do with that small battery for the bios?..that one has never been replaced.
Could that give this effect..?