What to do when start up hangs

Every now and again I can't boot up. just sits on the load screen. I've tried the computer forced shut down by holding in the power button. All I can do it turn off the electricity supply. I then get a warning that I did not shut down properly. For peace of mind I always the do a reboot.

I don't know it this is because the USB is connected , so I often disconnect the wfter I forace a shutdown. I have an issue (that another poster raised a post on too) where the bass station starts receiving messages, even when play is not in action, so today even though the USB was connected, the bass station was off, as I wanted to see if starting up the bass station after a full boot up stopped the messages issue (for info I also have a ReFace connected, but it's now powered up.

Sorry that last paragraph was just info, my real question is, what do I do when the boot up hangs on eth MPC startup page.,

Hold the power button for 10+ seconds. it will shut off. double check your sdcard though, make sure its still in good condition. (fsck (file system check)).

I've encountered this with a failing sd.

Cool thank you.