If when running School Days you are getting the error message "script version doesn't match" then there is most likely an issue with your game's registry data.
In the Start Menu, either in the Run Box or the Search box, type regedit and press Enter.
Navigate your computer's registry and find:
Check the values in the "Install" entry. They should look like this:
If your values are different, or don't exist, please update/add them. To add a new key value, select New from the Edit menu, or by right-clicking your mouse. More information can be found here.