[TYPO3-dev] BE form and ajax

[J. Lingott]

  Hi list,

on a plugin's backend form I am trying to implement some ajax behaviour 
which is invoked by an included javascript file. The invocation works, 
but all I am getting on the reply (either using my own ajax.php or the 
core one) is the following error.

|Fatal error: Cannot redeclare xdebug() (previously declared in Q:\data\worxtuff\tempsites\t3powder\t3lib||\config_default.php:488) in Q:\data\worxtuff\tempsites\t3powder\t3lib\config_default.php on line 492|

Anyone got an idea where that derives from?