Stack Trace Error Handler

[xanax]

I'm trying sugarcrm and it's kwite good. Programers and the comunity did remarkable job and it works right out of the box. I'm using crm for a week now and today i tried to log into crm and i've got bunch of red errors like this:

Notice: Undefined index: lock_homepage occured in /cache/smarty/templates_c/%%09^09B^09BB77A6%%Home.tpl.php on line 52 
/cache/smarty/templates_c/%%09^09B^09BB77A6%%Home.tpl.php[L:52](:StackTraceErrorHandler)
include/Smarty/Smarty.class.php[L:1265](:include)
modules/Home/index.php[L:112](Smarty:fetch)
/index.php[L:771](:include)
Notice: Undefined index: script occured in cache/smarty/templates_c/%%09^09B^09BB77A6%%Home.tpl.php on line 93

Can still see the main tabs, no admintabs error are shown in the midlle of the page..

For an hour i was looking for a problem and just after freash instalation on the same base i found it. In config_override.php
$sugar_config['stack_trace_errors'] = true;
After setting this on false evrything whent back to normal. So the question is what this variable do ? How it would get to that config and is Elvis still alive :>

Important!
» Operating system type and version DEBIAN 4.0
» Sugar Suite version Version 4.5.1b (Build 1246)
» Webserver type and version Apache 2.2.3-4
» PHP version 5.2.0
» MySQL server version 5.0

Ok i found option SHOW ERRORS in the administration panel. Why after enabling that option those errors make the whole thing to stop working ?