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