Hello, i've found the solution at:
http://www2.goldfisch.at/knowledge/224 , thanks a lot to Peter Pilsl for his information.
I copy part of Peter's solution (he used "nobody" as Apache user, I guess most of us use "apache" so you have to change that accordingly):
Only reboot of the system helped out of my crisis.
Solution: There were myriads of semaphore-arrays left, owned by my apache-user.
ipcs -s | grep nobody
Removing this semaphores immediately solved the problem.
ipcs -s | grep nobody | perl -e 'while (<STDIN>) { @a=split(/\s+/); print `ipcrm sem $a[1]`}'