AutoCAD .NET :: Reading In Mass DXF / DWG Files

i am developing some code to read in mass dxf OR dwg files, seperate the two, then convert each to a database to be read later. however, whenever i run it, i get this error: System.AccessViolationException:

Attempted to read or write protected memory. this is often an indication that other memory is corrupt.

     at AcDbDatabase.dxfIn(AcDbDatabase*, Char*, Char*)
     at Autodesk.AutoCAD.DatabaseServices.Database.DxfIn(String fileName, String logFilename)
     at ZahnerCommands.Commands.GetFiles()....line 72

here is the code that i have so far. i have been tinkering around with it for a few days and cannot seem to get it to work. the dxf file i have chosen works perfectly well, and i am using autocad 2011.

using
Autodesk.AutoCAD.ApplicationServices;
using
Autodesk.AutoCAD.DatabaseServices;
using
Autodesk.AutoCAD.EditorInput;
using
Autodesk.AutoCAD.Runtime;

[code]...