I have a class named DynamicLinkLibrary which does this:

 [DllImport("kernel32.dll")]
 private static extern IntPtr LoadLibrary(string fileName);

 protected virtual void Load(string fileName)
 {
  EnsureNotDisposed();
  if (LibraryHandle != IntPtr.Zero)
   throw new InvalidOperationException("Library already loaded");
  if (string.IsNullOrEmpty(fileName))
   throw new ArgumentNullException(fileName);

  LibraryHandle = LoadLibrary(fileName);
  if (LibraryHandle == IntPtr.Zero)
   throw new InvalidOperationException("Invalid DLL file name: " +
fileName);
  FileName = fileName;
 }

In WinXP this works fine, however, when I run it on Vista the result of
LoadLibrary is always IntPtr.Zero.  Using a relative path (same folder) or
absolute path makes no difference.  Can anyone help?  This is stopping me
from migrating an app to Vista!

Thanks

Pete