I'm guessing that it has something to do with administrator privileges.
Try going to control panel. From there, go to User Accounts and Family Safety - click on the title, specifically. From there you should find another screen with options to configure User Accounts, Parental Control, Credential Manager, etc.
You'll want to take a look at your account settings, so go to User Accounts - again clicking on the title. This should take you to a screen with your account name and picture in a box at the right hand side...mine is "Kathryn" with an icon of an orange flower : P
Underneath that it should say something like standard user, or "Administrator". If it says Standard User, then I'm guessing the reason that you cannot install the .dll is because you don't have the privileges to do it. You can change your privileges by logging on as an account that is an Administrator, going to the same screen with the icon/name as above, switching to editing your own profile by clicking on "manage another account", and then pressing "change account type". Try installing Charsiesis again after changing your account to administrator. If that doesn't work, or if you're classified as Administrator already, then we'll have to think of something else.
If anything there was unclear, then please tell me ^^
