I have been getting 'access violation reading location' errors
occasionally in my app. I have debugged this and found it is one of my
interop functions. Am I doing anything wrong here? The unmanaged
function takes a pointer to some bytes in memory and a long, and
returns a pointer which points somewhere into those bytes based on the
long value.

My interop code is like so:

   [DllImport("ImageFile.dll", EntryPoint =
"?PB_SkipBytes@@YAPAEPAEJ@Z", CallingConvention =
CallingConvention.Cdecl)]

   public static extern IntPtr PB_SkipBytes(IntPtr pIn, int
bytesToSkip);

public static Byte[] SkipBytes(Byte[] bytToDecompress, int
intBytesToSkip)
   {
       IntPtr pbData;
       IntPtr pbByteArray;

       System.Diagnostics.Debug.WriteLine("Entering Skipbytes
function");
       // Pin the array in memory so the garbage collector can't move
it around
       System.Diagnostics.Debug.WriteLine("About to pin array");
       GCHandle pinnedArray = GCHandle.Alloc(bytToDecompress,
GCHandleType.Pinned);
       System.Diagnostics.Debug.WriteLine("Pinned array -
byttodecompress length is " + bytToDecompress.Length);

       // Get a pointer to the beginning of the pinned byte array
       pbByteArray = pinnedArray.AddrOfPinnedObject();
       System.Diagnostics.Debug.WriteLine("Got pointer");

       // Call the skip bytes function and get a pointer to the
remaining uncompressed data
       System.Diagnostics.Debug.WriteLine("Skipping " + intBytesToSkip
+ " bytes");
       pbData = PB_SkipBytes(pbByteArray, intBytesToSkip);
       System.Diagnostics.Debug.WriteLine("Called");

       // Calculate the size of the new managed array and allocate
       int intNewCompressedArraySize = (pbByteArray.ToInt32() +
bytToDecompress.Length) - pbData.ToInt32();
       System.Diagnostics.Debug.WriteLine("Calculating new array
size");
       byte[] bytBuffer = new byte[intNewCompressedArraySize];

       // Copy the remaining uncompressed data into the buffer
       System.Diagnostics.Debug.WriteLine("Copying to new array");
       Marshal.Copy(pbData, bytBuffer, 0, intNewCompressedArraySize);
       System.Diagnostics.Debug.WriteLine("Copied to new array");

       // return buffer and free memory
       pinnedArray.Free();
       return bytBuffer;
   }