We are seeing strange fatal errors on 1 fairly big installation. Error occures on few very specific function calls. We've traced it back to zend_execute_api.c, call_user_function_ex which checks on no_separator value and returns failure if variable has value >0. 

Ratio of errors is approx 1-2% of all pageviews (=>min 5000 failure cases per day) on Solaris based installation. However we do not see this on Linux cluster, running same codebase, getting approx the beating if not higher. 

To make things more weird - we saw the error 5x in one evening on low-loaded Linuxbased devel box (4.06) but not before nor after this day.

Errors started to surface on Solaris version at upgrade to 4.04 and are present on 4.06 as well. Note that we've made quite many mods to PHP and prob might be caused by our own actions.

Though we will dig into it on our own in a few days it would be great if someone fluent with internals of call_u_f_ex could at least point us to possible causes & things to investigate.

wbr,
toivo