Windows 7: PC hanging on Windows 7 Startup screen

Hi All,

I have been running the same installation/hardware build for 6 months+ now with zero issues. As of recent, my pc will hang sometimes when booting up. It doesnt freeze, as I can still see the windows logo kinda moving. It will just sit at the 'starting windows' screen. I have to reboot to move on.

Now it doesnt happen all the time, just randomly. An sometimes it might take several attempts before it actually boots into windows. The only changes I can remember doing prior to this issue was updating my nvidia drivers, and adding usb extension cables for my keyboard and mouse. Apart from that it has been the same.

My PC specs are as follows;

OS:Win 7 64 bit Ultimate (SSD OCZ Vertex 3 120gb)
CPU: i7 980x
Ram: 12gb (6x2gb) G.skill 2000mhz
GPU: Sli gtx 580
Motherboard: Asus Black Rampage Extreme X58

Update: Have tried doing a system repair and it come up with 'startuprepairoffline', problems listed are unknown....