Does this happen with any other software ie freezing?
Test with internet unplugged.
Look on task manager to see if anything is hogging cpu on Processes.
I've just fitted some worktops into a friends kitchen, using mason mitres.
These were replacement tops, with tiles already in place on the walls. I had some trouble fitting them in as the wall tiles made it difficult to scribe the mitres accurately.
Any techniques I could use, apart from...