We have not had any similar issues with the DZ77GA-70K; for troubleshooting purposes, though, we would recommend the following:
1. Ensure the drives are properly recognized on the BIOS.
2. Test with a different DVD driver to narrow the issue properly.
3. Remove the RTC (Real Time Clock) battery and leave it out for 30 minutes. After this period of time, insert the battery back in and turn the system back on; if it displays POST messages, go into BIOS Setup Utility by pressing <F2> during the boot process. Once in the BIOS setup utility, press <F9> to restore BIOS default settings. Reset any customized BIOS settings. Clear all DMI event logs, which are located in the Advanced/Event Log Configuration section of the BIOS Setup utility. Press <F10> to save the new settings and reboot the system.
4. Proceed to back your information and do a clean installation of the Operating System using the latest drivers from our website since this seems to be an Operating System instead of a hardware failure.