Crash due to invalid pointer

Hallo, I am a newbie concerning Collada.
So far I’ve written a reader which reads among others the vertices of the meshes in a collada file. v1.4.
This works fine so far.
Today I included nvwa (memory leak detector) to check my code.
Unfortunately it lets my program crash at this code:

daeElement* el = root->getDescendant("authoring_tool");
string s;

The problem is the function getCharData(). The problem disappears when I comment it out.

The error message is:

delete: invalid pointer 0181ABF0 ()
*** Checking for memory corruption: START
*** Checking for memory corruption: 0 FOUND

Does anybody know what the problem could cause?

I built the 1.4 version with VC2010, adding

#define XML_PARSE_HUGE 524288

to daeLIBXMLPlugin.cpp due to an error message from VC.