Game freezing on AJAX request

I don't know if this should go in the bug report section, but this is my situation:

I need to do two external AJASX calls. The first one is hardcoded(www.site.com/ajaxForm.php?varA=firstList) That result fills a drop-down box. When the user clicks on a menu item, it's supposed to send another AJAX call (www.site.com/ajaxForm.php?varA=secondList&varB=selectedItemFromFirstStep)In Firebug, I can see that the second URL is being called correctly (I can copy the address and load it in another window), but the entire browser window freezes. Reloading doesn't work. I can only close that window, and open another one.

When I use a project JSON file, the app works correctly, but I need to get the info from a database.

I hope that's enough info. Thanks for your help

Are there any browser errors when it freezes?

There are no errors in the console. The browser complains that the script has stopped responding. I've reproduced the error in a capx - dl.dropbox.com/u/12722403/Construct2/JSONbugTest.capx. The only external plugin that I'm using is the comboBox by septeven (http://www.scirra.com/forum/topic46969.html)

I think it had to do with a misconfigured JSON file. I'm going to keep tinkering. Thanks for the help.