pthread_mutex_lock error on HP-UX 11i

[Ramsunder S]

Hi,
We are faced with a problem wherein our programs call a pthread_mutex_lock call on HP-UX 11i and fails with error 13 or 32.
We are using a PTHREAD_MUTEX_ERRORCHECK type mutex and it is being initialized.
Also, we observed that this error is given only when the number of processes trying to access that mutex goes beyond a certain level.
For e.g., if we have 20 processes trying to access the mutex, the first 15 are able to acquire locks on it while the last five are not. Reducing the number of processes to 15 circumvents this problem.

Any help in this regard is appreciated.
Regards,
Ram.