Epson NX400 Scanner drivers won't install;error message.

That is a weird message. I am just wondering, did you disconnect the scanner from the computer before trying to install this driver? At least with some printers/combos, the driver downloads require you to disconnect the printer so the driver will "install properly" and then reconnect it after the driver is finished downloading. If you didn't do it that way with the scanner, try it and see what happens. You might be able to "fool" whichever system is having an "issue" with the install that everything is OK.