well, i am feeling rather stupid... :
System: LMDE with Updatepack 3 on new ACER Laptop and 686-PAE Kernel
Everything worked fine until after some software additions, Updates etc. (still setting the system up for work).
(a) At BOOT, internal keyboard works at GRUB screen, but NO FUNCTION at Login-Screen.
(b) a fresh pluged-in a USB keyboard works for log-in!
(c) after login, the internal keyboard works fine
'dmesg | egrep keyb' says:
2.613410] inpit: AT Translated Set 2 keyboard as /devices7platform/i8042/serio0/input/input0
What is the problem, I really don't know what to do....