I have a web server with apache 2.0 installed. It comes with Zend Server install pack. When I’m trying to debug my php files apache serves a blank page with 503 service unavailable. Of course slow server-side code is tying up Apache requests for far too long, but I need it to wait, until my debugging comes to end.

When I call to the page from a browser it launches ZendStudio debugging my PHP script (request redirects Zend Debugger module). I debug through my script and if I finish debugging in 120 seconds, I normally return to the browser. When it takes more than 120 seconds the browser displays '503 service unavailable' and I can't return to page output. I have even forced 'max_execution_time = 300' 'max_input_time = 600' in php.ini and 'TimeOut = 500' in httpd.conf. No matter whether it is Opera, IE or Firefox. I spent two days googling it, no right answer until now.