Here is a thread with instructions for how to deal with a bad installation of Reader Library on a PC. It includes instructions for Windows Vista. See post #2.
https://www.mobileread.com/forums/showthread.php?t=73550
EDIT: If you are confused by the name eBook Library in the referenced posts, it's because that's what Sony used to call their software before they switched to the name Reader Library. But the instructions might point you in the right direction. It looks very similar to the Mac uninstall/reinstall process.