One way to disable the splash screen that appears when you start SAP Business One (the movie that plays with the water drop, just before the sign on screen) is just to rename the file in the program directory.
I found mine in this directory:
C:\Program Files\SAP\SAP Business One
The file name is "sapss", right click choose Rename and change the name to something else (anything else). The next time you start SBO, it will not display.
It stands to reason that you could replace this file with your own…as long as it has the same file name. If you need help creating your own movie file, we can help you develop that too.
When you upgrade to a new version, you will probably have to perform this activity again.

Thanks to Ed Monk of SBONotes.com