[Pyro]

такая вроде работает

Код:

uses psapi;

function ProcessFileName(PID: DWORD): string;
var
  Handle: THandle;
begin
  Result := '';
  Handle := OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ, False, PID);
  if Handle <> 0 then
    try
      SetLength(Result, MAX_PATH);
      if GetModuleFileNameEx(Handle, 0, PChar(Result), MAX_PATH) > 0 then
        SetLength(Result, StrLen(PChar(Result)))
      else
        Result := '';
    finally
      CloseHandle(Handle);
    end;
end;