Troubleshooting

• IT WON"T START OR FILE DISAPPEARED --> CHECK ANTI-VIRUS: For locking screen this software blocks keyboard and mouse globally. That is, by most antivirus software, seen as suspicious and they block, delete or quarantine such software automatically. You need to add .exe of this software file to exclusion list in your antivirus or temporarily disable antivirus until you find problem cause.
• IT WON'T START --> ADMIN RIGHTS: This software requires to run with admin privileges. If you are already logged in with administrator account type it will try to launch itself as admin but in some cases you must manually right-click and select "Run as administrator". 
• IT WON'T START --> FOLDER PERMISSION: This software requires write permission on folder where you placed it (its .exe file). By successfully running as administrator this permission is usually obtained automatically but in some cases you need to right click on folder, go to properties and allow full access to everyone or at least give write permissions to that folder for current account. Sometimes its enough to right click, go to properties and clear Read-only checkbox.
• IT WON'T START --> UNBLOCK EXE FILE: For most downloaded files windows mark them as unsafe or blocked. In some cases you need to right click downloaded .exe file, go to properties and check Unblock checkbox.
• I SEE WEIRD PIXELS ON MY LOGIN SCREEN --> KNOWN ISSUE. Sometimes when screen lock is not dimmed or locked (idle time) weird color shade effect may appear on screen most often on windows login screen. Don't worry your screen is not damaged. Its purely esthetical effect and not permanent. Will be addressed if more people report it.
• IT WON'T RUN AFTER BOOT --> CHECK TASK SCHEDULER: software uses task scheduler to tell windows to run it on boot. In your start menu type taskschd.msc and in task scheduler you should see F4CIO.ScreenLock task. Insure its pointing to right exe file and is set to run with highest privileges. 
• OTHER ISSUES --> SEE .LOG FILE: software creates and starts writing to .log file immediately on run . Log file is beside .exe file. It can help you see if there is any error or track down other issues.
• OTHER ISSUES --> SEE WINDOWS EVENT LOG: in your start menu type eventvwr.exe and in Event Viewer go to WindowsLogs>Applications. Search for any error especially mentioning .NET.