In the last episode (Sep 08), Martin Nilsson (Opera Mini - AFK!) @ Pike (-) developers forum said:

Someone knows anything about this problem on a solaris machine?

Wait thread: waitpid returned error: 0

The output is from signal_handler.c, and there is an issue reported on FreeBSD for this. http://community.roxen.com/crunch/show_bug.cgi?id=3917

I haven't seen the error on FreeBSD in ages. If you're running Solaris 10, try running the attached dtrace script in the background and see if it ever prints anything. It will trace any wait* syscall that ends up failing with an errno other than ECHILD (which is the only errno I ever see)