php code compiles, produces good html output, but crashes when put through browser

Hi, Need some help with debugging procedures. This is a postgresql/PHP running with PHP 5. I have used both IE7 and mozilla 5.0 with this file. The postgres part works fine, and the html that is generated is OK, but the .php file hangs when I run it through the browser. I have two tables -- data_series and data_sets with a 1-many relation between the data_series and data_sets. My page first displays the data_series in a <select>. Then it pulls the data_sets belonging to user selected data_series and displays them in a select. There are links to .php files to process the selected data_set. My code http://demog.berkeley.edu/~maryfran/memdev/get_data_set.php compiles OK when I run php on it from the shell. It produces html forms which will load into the browser and run as expected. However when I try to run the .php file in the browser it parses the head, displays the title, and then hangs. No error messages are displayed, even though I have called error_reporting(E_ALL) at the very top of the .php file. I had an echo statement on each line of php code. None were printed out. I checked permissions on the .php file. Changing them did not improve the situation. I need some basic debugging tools that I don't have to figure out what is going on. Alas, I think this code would hang before it got to the debugger! Any advice is appreciated. At this point I am clueless. Mary Anderson