Error "Debug Assertion Failed!"

Hello expert!

I am working for a customer of us, where I am responsible for a server written in C++. The company uses Microsoft Visual Studio 2005. While going through the code to see better how it works with the debugger, I came up with an error message that reads:

Microsoft Visual C++ Debug Library
_________________________________________
/!\ Debug Assertion Failed!
   Program:...
   File: .\xstring
   Line: 2061

   Expression: invalid null pointer.

   For information on how your program can cause an assertion
   failure, see the Visual C++ documentation on asserts.

  (Press Retry to debug the application)

  [ Cancel ] [ Retry ] [ Ignore ]

I read on the Internet that there can be several reasons, like
* Problems with ActiveX or OLE
* Moving binary code from one Microsoft IDE to the MSVS 2005
* The parameter with the file path & file name had not the extension (.txt missing).

To my knowledge, none is the case here. We do not use OLE, have migrated anything, or pass a file URI that has an extension.

So far my question. What information do you need to analyse my problem?

The exact point where I get the error is the line
   m_pEnv = Environment::createEnvironment();

in the code snippet attached, where the variable was declared as

oracle::occi::Environment *m_pEnv;

Before getting the error message, one more message occurs. But this is a message we always get. The reason may be a problem with the ORACLE installation, my project manager told me. This first error message reads:

Microsoft Visual Studio
__________________________________________________________
/!\  Windows has triggered a breakpoint in indizierer.exe
    This may be due to a corruption of the heap, and indicates a bug in
    indizierer.exe or any of the DLLs it has loaded.

   The output window may have more diagnostic information

                                             [ Break ] [ Continue ] [ Ignore ]
__________________________________________________________


(The output window is empty)

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DBEnvironment::DBEnvironment(void)
{
	TRACE_LOG(H_TRACE_TRACE2, __FILE__, __LINE__,"Constructor -------- START Enviroment --------\n");
//	m_pEnv = Environment::createEnvironment(Environment::OBJECT);
	try
	{
#ifdef WIN32
		SetEnvironmentVariable("NLS_DATE_FORMAT","YYYY-MM-DD");
		SetEnvironmentVariable("NLS_TIMESTAMP_FORMAT", "YYYY-MM-DD HH24:MI:SS");
 
		m_pEnv = Environment::createEnvironment();
#else
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