PHP auto_prepend_file causes xdebug profiler to fail

Question

I use xDebug 2.5.5 on a Windows 7 machine running Apache 2.4 and PHP 5.6. xDebug profiler works ok except when I use a php auto_prepend_file

in php.ini

auto_prepend_file = "C:\path\to\init.php"

or in Apache Vhost

php_value auto_prepend_file "C:\path\to\init.php"

In either case, adding this directive will cause the generated profiler snapshot cachegrind.out.####, to be corrupted somehow. I cannot open it either in PhpStorm (my IDE) or using WinCacheGrind. In addition, I cannot delete the snapshot until I kill the Apache process

WinCacheGrind error

Access violation at address 004A5908 in module 'WinCacheGrind.exe'.

Read of address 00000000

PhpStorm error

Incorrect Profiler snapshot format: Incorrect name format

Any advice?

PS: I voted to close my earlier issue that was misslabeled b/c I thought my problem had to do with PhpStorm not xDebug