Hi Mark and welcome to PC Help Forum.
Let's see what process is causing this freeze. Right click on the task bar and select Task Manager. Click on the "processes" tab and then click on
CPU twice, so that the processes using the most amount of
CPU % are at the top. Keep it open and carry on working...when you freeze next time, make a note of the process name at the top (it will more than likely show 100%). Let us know and we'll take it from there.