Installed Ccleaner today on my login (administrator) and worked normally. Tried to use the program on my wife's login and got message "reuires Window 7 or later" I do run windows 7 ???
Odd one, is if your wifes account set to run in compatibility mode for XP or Vista?
Also - Are you using CCleaner Pro version?
The free version only works on the user account where it is installed, Pro can clean all user accounts.
perhaps helps a microsoft-answer for another installationsproblem ;-)
try the installation for your wife from folder "downloads" <--- move the installer in this folder and install it from there
this is from a troubleshooting