ATAPI Incompatible

Help needed with an ATAPI Incompatible message when I boot.
I didn't change anything in my system, but the error appeared out of
the blue. I checked all cables ... they're fine. Everything was fine
in this configuration for years! The only thing I recently did was
install some SW, but even after this everything worked properly for a
good while.

Now Comes this Message when booting up:

Sec Master Drive - ATAPI Incompatible
Sec Slave Drive - ATAPI Incompatible
Press F1 to continue

If I do so, the systems does not find any of my drives, but boots
perfectly from HD.

Any ideas. i'd be gratefull for help.
DuDu