Running Sony Vaio PCV-RZ22G desktop with SONY DVD RW DW-U12A burner. Whenever I put either a CD or DVD disk (self-burned) into the tray, it locks up computer completely; freezes mouse, no Control/Alt/Delete, nothing works; have to power off using power switch on computer. Defective drive? Device manager shows no problems, no IRQ conflicts, etc. Has always worked perfectly in the past. Any suggestions to test burner or otherwise? Thank you in advance.