rMBP gets stuck on spinning circle when restarting

Hello

This is my first mac in more than 10 years so I'm not sure exactly what to do.

My rMBP gets stuck on the spinning circle on a black screen whenever i restart. I have waited a long time but it does not change. I have to do a force shutdown with the power button for it to start again. I am currently on Yosemite. This problem was also happening on Mavericks.

It is a 13" 2014 rMBP with an i5 processor and 8 GB memory.

Thanks for your help.