Just downloded and look. The other 3 png are there exept what you mentioned. I would say that if this was a WINDOWS 9x, or even XP or 2000, I bet its just the logo.sys logow.sys etc.. file. But if it Linux, i would not know what that would be. I don't think that PNG file is embeded into ADVMAME, ADVMENU itself. So it has to be the OS BOOT process.