Access denied while getting process path

Finally I managed to solve it. As it turned out there is new function in Vista and above for getting process path and new process access (PROCESS_QUERY_LIMITED_INFORMATION):

QueryFullProcessImageName

Here is the code that works from non-elevated process:

    private static string GetExecutablePathAboveVista(UIntPtr dwProcessId)
    {
        StringBuilder buffer = new StringBuilder(1024);
        IntPtr hprocess = OpenProcess(ProcessAccessFlags.PROCESS_QUERY_LIMITED_INFORMATION, false, dwProcessId);
        if (hprocess != IntPtr.Zero)
        {
            try
            {
                int size = buffer.Capacity;
                if (QueryFullProcessImageName(hprocess, 0, buff, out size))
                {
                    return buffer.ToString();
                }
            }
            finally
            {
                CloseHandle(hprocess);
            }
        }
        return string.Empty;
    }