My laptop is frozen/unresponsive when I open it

Whenever I open my MacBook to the start-up/log-in screen, I can't do anything. My cursor does not appear, and pressing keys does nothing. The only way I can get past this is to shut the laptop down by holding down the power button and then turning it on again. For some reason this works, but it's annoying and time consuming to have to do this every time as opposed to just being able to log-in when I first open it up, as I should be able to.

I've tried shutting it down and making it sleep before shutting the lid, but the next time I open it, it still freezes at the log-in. I just recently got it sent off to be fixed by Apple for the second time in 3 months for an unrelated issue. Now I am having this problem and I'm wondering what I can do.

Thanks.