NAV 2013 & Windows 8 Shutdown.

I updated to NAV 2013 a short while ago whilst running Windows 7 with no issues. Last week I upgraded to Windows 8 Pro & since then my PC would not shutdown of restart when selecting from Windows. I tried everything to solve this (checking hardware/drivers etc) with no joy. Anyway, yesterday I had a live tech session from Microsoft who controlled my PC to try & sort it. To cut a long story short it seems NAV 2013 was the culprit, especially when auto-protect was enabled. When this was disabled shutdown worked normally. Anyway we uninstalled NAV online, rebooted & reinstalled it again. Unfortunately with auto-protect enabled the problem returned. I will also point out that whilst I was using NAV 2013 the built in Windows Defender was disabled. In the end we had to uninstall NAV again & I have reverted to Windows Defender for the time being. Bear in mind I still have a NAV subscription running which I can't use. I understand that the 2013 versions are supposed to be compatable with Windows 8.

Has anyone else had this issue & will there be a fix for it?