Macbook boots up to log in screen but wont go any further. I have booted in safe boot just fine. I dont want to have to reinstall OS. Any suggestions?

It starts up fine until I log in and then it just stays on the northern lights screen. The mouse moves and all but I wont open the home screen. I have booted in safe boot and it works fine. Virus? is there any way I can fix this without reinstalling OS? I have not set up Time Machine either and I cant now because in safe mode the USB ports don't work.

Thanks