Nothing new and nothing surprising, but it still was painful to find out:
Do not use valgrind or helgrind in combination with the c++ compiler options -p and -pg for profiling.
This gave me some strange behavior of my app with sleeps not sleeping. I only had a crashing application, no clue what might be wrong with my code and the error message “Profiling timer expired”.
Just switch off the profiling options and everything was find, except the errors that I wanted valgrind to find for me.