I cannot close Cashbook. It keeps coming up with an error or is showing as "not responding".
Some program errors may cause the program to become unresponsive or prevent you from closing it.
This post describes how to force-close Cashbook (or any other Practical Systems programs) through your Windows Task Manager.
Step 1: On your keyboard, either
Step 2: Left-click on Task Manager or Start Task Manager (whichever option appears).