Screen unlocking bug?

I'm not sure if this is really a bug or if its a Mac exclusive bug ( I use a Mac) or if its only from my computer but there are a lot of times where as I'm playing i can't unlock the screen anymore and i can't even click on the map to change camera angles. This sometimes affects my gameplay as during a fight this bug would kick in and i can't see anything thats going on. I can fix it by alt tabbing out and coming back in and moving the camera angle by dragging the square box on the map around. In addition there are some cases where i couldn't lock my screen back in. The Y button didn't work but holding space would and alt tabbing out would usually fix this problem. Again not sure if its just my computer or if it really is a bug :/