I just found out how to disable the splash screen of Pop-Up Stopper Free Edition. It worked for me.
1. Make sure Pop-Up Stopper is not running.
2. Go to run, type in regedit. Click on OK
3. Go to HKEY_CURRENT_USER/Software/Panicware/Pop-Up Stopper Free Edition
4. Look for ShowSplashScreen and change the value to no replacing yes