I didn't see anywhere in the sr4 readme telling me to reboot after installation. I didn't and P5 loaded and ran fine (for Poser, that is). While there are some programs that do ask you to reboot after installation, most nowadays are systems utilities and the like. And even then, the programs don't become corrupted if you don't reboot, they just don't work properly until you do. The only reason I know of for a reboot is to force a re-read of the registry. Not rebooting should have no effect on the program files themselves. IMO, if it does, there's a serious flaw in the program. It's beginning to look to me that sr4 is suffering from the same plague since p5's release: works okay for some, doesn't for others. Sorry I can't be of any more help.