Same here, I thought it was a hardware issue at first until I found this thread. MWB was running wild processes all over the place prompting me that real time protection was turned off (apparently it did so by itself).
Only solution for me was to forcibly uninstall MWB through Revo Uninstaller, as I couldn't even uninstall it directly.
A shame that a program meant to protect you starts running wild with your PC. I'm a premium user, so hopefully they get this fixed soon. Always been happy with Malwarebytes, but this is a big fail here.
The issue must haver started after 14:00 GMT+1, as I had no trouble up until that point. Only logged back on in the evening and the problem started immediately.