Sure, under normal circumstances it's content is as follows:


But the actual contents doesn't matter, as the crashing still happens even when the file is empty.
If been using this file for a long long time now without a single problem (pre my laptop migration that is).

I just installed dbg 3.2.3, php 4.4.7 (as apache handler), apache 2.0.55 and tested your auto_prepend_file and phpinfo() call in the main file. It worked stable. No crashes.
What I'd recommend you is to try to comment off all extension=, zend_extension_ts= lines in your php.ini and give it one more try.

Please don't forget the Vista part.
I've just disabled all extensions in PHP and for Apache I disabled the SVN & DAV modules (the only ones added by me, the rest is default).
Still no luck.
If uploaded 2 versions of PHP info on my server:

* DBG extension disabled, auto_prepend_file on
* DBG extension enabled, auto_prepend_file off

Combining both results in a server crash. Honestly I'm running out of ideas.
If I would manage to find a base from which it works so that I could eliminate everything step by step I would be able to solve it, but even the simplest configuration refuses to work...

I also still have problems with the sun server, So I downloaded the latest version of PHPed (5029 / 3.2.3), installed DBG and changed php.ini to autoprepend a file and it crashed.

So I did some more testing, and found when having an php exec; command at the end of the file it is not crashing!!!!

It seems to be different if php script is ended by exit or not (when auto_prepend_file is used). So there are 2 solutions now:
1. remove auto_append_file from php.ini
2. add exit() or <?php exit() ?> to end of the script
hope this helps to find this nasty bug.

KASI

This problem is caused by php itself, not by debugger. Some of the crusial pointers inside php may get bogus values at some points and cause the crash. It has no relation to the debugger, although it's debugger uses the values, interprets them and may crash on them.
You may try to search for "nirvana" word in the php sources and find this:
main.c: 967: (php4.4.2)
main.c: 1265: (php5.2.1)
/* EG(opline_ptr) points into nirvana and therefore cannot be safely accessed
inside zend_executor callback functions. */
Needless to say that EG(opline_ptr) is a crusial pointer for the debugger or it would not know the line numbers and opcodes.

Having that said I'd also add that I found a workaround and now debugger works pretty stable when auto- prepend / append files are used. New version (3.2.6) will be released with PhpED build 5031.
All customers experienced this problem are welcome with your requests to get the modules right now: http://shop.nusphere.com/contact_us/

Here's me confirming that the workaround does the trick, everything works fine again.
Thanks a lot for the help Dmitri!