Z68-Ext4 reboot issue

[bchat33]

I have this mobo -

ASRock Z68 Extreme4 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard in this case - Corsair Vengeance Series C70 Military Green Steel ATX Mid Tower Computer Case When I use the re-set/reboot button it seems to shut the OS right down and the "Windows didn't shut down correctly" screen comes up and "Start Windows Normally" is highlighted. Hitting ENTER brings all back to normal. I have never had a machine do this and am wondering if it is an issue/oddity with this mobo?, mobo/case combo?, some error in the wiring somewhere?. I have checked and double checkd the mobo connections and all seems well. I have an Z68Ext4Gen3 mobo in a white version of the same case, and it reboots OK. Any suggestions appreciated. Windows Ultimate x64 if the OS.