Error occurs when they try to reinstall the program again.
Uninstall then delete the following folders
C:\Program Files (x86)\PracSys\Stockbook
C:\Users\\AppData\Roaming\PracSys\C\Program Files (x86)\PracSys\Stockbook
C:\ProgramData\PracSys\C\Program Files (x86)\PracSys\Stockbook