Problem with the following procedure which generates GPF because it needs GetLongPathNameW instead of GetLongPathNameA.
In addition, the buffer is one byte too small. 
Fix is in code below.

function LongPathName(const FileName:String):String;
var
  BufferSize: DWord;
begin
  // "GetLongPathNameA" available only for Win2000, WinXP or Win2003, or newer !
  if (Win32Platform=VER_PLATFORM_WIN32_NT) and (WindowsMajorVersion>=5) then
  begin
(* 
// --------- BEGIN REMOVED CODE -----------
    if TeeKernel32=0 then
    begin
      TeeKernel32:=TeeLoadLibrary(kernel32);

      if TeeKernel32<>0 then
         @GetLongPathName:=GetProcAddress(TeeKernel32,'GetLongPathNameA');
    end;

    BufferSize := GetLongPathName(PChar(FileName), nil, 0);
    SetLength(Result, BufferSize - 1);
    GetLongPathName(PChar(FileName), PChar(Result), BufferSize);   
// ----------- END RREMOVED CODE ----------
*)

    // 2/19/2009 ------------ BEGIN CODE ADDED -----------------
    if TeeKernel32=0 then
    begin
      TeeKernel32:=TeeLoadLibrary(kernel32);

      if TeeKernel32<>0 then
         @GetLongPathName:=GetProcAddress(TeeKernel32,'GetLongPathNameW');
    end;

      // returns length (including #0) of LongPath (or 0 if not found or error)
    BufferSize := GetLongPathName(PChar(FileName),        // lpszShortPath                   
                                  PChar(Result),          // Out lpszLongPath               
                                  0) ;                    // cchBuffer                      
    SetLength(Result,                                                                         // ''
              BufferSize) ;                                                                 
    GetLongPathName(PChar(FileName),                       // lpszShortPath                  
                    PChar(Result),                         // Out lpszLongPath               
                    BufferSize) ;                          // cchBuffer                      
    If BufferSize > 0 then
    SetLength(Result,                                      // remove #0                       
              BufferSize - 1) ;                                                              
// 2/19/2009 - END FIXED CODE ADDED
  end
  else
    result:=FileName;
end;