Parellization

[sst168]

Hi guys,
I compiled cp2k-2.1.331 with gfortran 4.4 and openmp. And the problem
is that
when the code ran with more than 4 cores in a few senconds, the code
seemed stopping to
write output information into the output-file, but the code still ran.
When I changed 4
cores to 2 cores, the code was OK and a lot of information was wrote
into the output-file.
Did anybody encountered this problems and how to deal with it?

BTW, my conputer configuration is:
CPU: Intel Xeon E5405 (2.0GHz, 4 cores and no multithreads).
Operating systerm: Fedora release 8.

Looking forwards your reply.

Regards,
S.T. Sun, Chemistry,
The Chinese University of Hong Kong