Why won't my macbook reboot after installing usb drive?

I have a mid-2010 MacBook Pro running Mavericks and I installed a 3.0 usb express card. I installed the recommended driver and rebooted but now I'm getting the spinning thingee under the apple logo on the gray screen. I restarted in safe mode but the keyboard wouldn't work. So I held down option and booted up and was able to run disk utility but it said everything is okay. Any ideas?