Massive problems today installing my Epson scanner, which worked fine up until a day ago. Windows would start installing the driver, then error, saying the system cannot find the file specified. A bit of digging around suggested looking in $windows$\inf\setupapi.dev, (or in my case Windows 7 64 – setupapi.dev.log).
Search through that for “cannot find the file” and just above it should refer to a file location and the file it is looking for, in this case usbscan.sys. I searched through the windows folder and found it, dropped it into windows/inf, which is where it was looking and the Scanner installed straight away. If you have this issue with other devices, looking in the api log to see what file is missing would be a good place to start, then see if you can drop it where it needs to be. Hope this helped someone.