PHP gets weired

Hello everyone,

I have a strange behaviour on my solaris 8 machine.
Every two or three hours PHP brings error messages.
1. Not able to run sendmail when using mail function
2. When using exec to run a OS program there comes unable to fork
3. Doesn't know the pfflib functions anymore

The rest of PHP runs just fine.
After restarting apache 1.3.26 with apachectl stop and apachectl start
everything works just fine for the next two or three hours.

This behaviour come wether I use PHP 4.3.8 or PHP 4.3.9

I compiled PHP with:
'./configure' '--prefix=/usr/local' '--without-mysql' '--with-oci8'
'--with-zlib' '--with-pdflib=/usr/local' '--with-gd=/usr/local'
'--with-jpeg-dir=/usr/local' '--with-png-dir=/usr/local'
'--with-freetype-dir=/usr/local' '--with-apxs' '--with-oracle'
'--with-crack=/usr/source/cracklib-2.7' '--with-imap'

There are no error messages in the log files which lead me to the
problem.

Greetings Markus