Sorry, I understand that my question sounds crazy, but that's what happened:
I had a working Maple program and Maple 15 installation on Ubuntu 11.10 64 bit
After I updated to Ubuntu 12.04 , Maple 15 starts, but returns almost all (except most primitive) integrals unevaluated.
My old working worksheets not return all integrals unevaluated.
Same with Maple 14.
I have no idea what could have happened...