I just downloaded the new version of dbg, and it is crashing Apache.

I am running:
Apache 2.2.4
PHP 5.2.1
XAMPP 1.6.1
php_dbg 2.15.5
Windows XP SP2

My PHP extension_dir = "C:\xampp\php\ext\"
I have added extension=php_dbg.dll to my php.ini fiile.
I added:
[debugger]
debugger.enabled = true
debugger.profiler_enabled = true
debugger.JIT_host = clienthost
debugger.JIT_port = 7869
to the php.ini file as well.
I put php_dbg.dll-5.2.x in C:\xampp\php\ext\ and renamed it to php_dbg.dll

When php_dbg.dll is in the c:\xampp\php\ext\ directory, accessing any pages via a browser immediately crashes both Apache processes that are running. If I take php_dbg.dll out of the c:\xampp\php\ext\ directory, then Apache does not crash.

I am planning on using PHPEclipse when Apache doesn't crash anymore. But just testing a php_info() page in my Firefox browser is crashing Apache.

Apache 2.2.4 makes absolutely no sense if you want to debug your php scripts.
Just for your info, there are many posts about this version.

Regarding Apache 2.2.3 you may try NuSphere TechPlatform 5.0, it comes with php 5.2.1 and apache 2.2.3 and works stable with dbg 2.15.5