Brush Tool Freezing as select tool

I’m using a 24hd Cintiq with a Macbook Pro from 2009 with 8 gigs or ram and running Yosemite. Running into this problem. Every few minutes, my brush tool will turn into the select tool and then be unable to turn back. I have to reboot my computer to get it working again. I found this happening if I did ctrl z as well. But it seems to happen regardless. I ordered an imac to hopefully remedy this problem, but wondering if anyone else has run into this. Super frustrating.

You should download the latest patch release version for
V5.5 from the “My Downloads” section of your account.