Cubase LE 5 + Win 8.1 64bit

After system reinstallation the problem has been appeared. Every time I want to close or switch Cubase project sytem is becoming busy and not responding even to Ctrl+Alt+Del combination. Though any other software using ASIO works well.
P.S.: Win 8.1 64bit, Cubase LE 5, ESI Maya 44XTe