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:
HKEY_CURRENT_USER\Software\Overflow\SCHOOLDAYS HQ\Install
Check the values in the "Install" entry. They should look like this:
"AllUse"=dword:00000000
"DiskCheck"=dword:00000000
"FullInstall"=dword:00000001
"Program"="SCHOOLDAYS HQ"
"Version"="1.00"
"Script"="1.00"
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.
Copy the following text to a text editor and save it as a registry file, such as "schooldays.reg". Then run the registry file and it will edit your School Days registry entries for you.
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Overflow\SCHOOLDAYS HQ]
[HKEY_CURRENT_USER\Software\Overflow\SCHOOLDAYS HQ\Install]
"StartMenu"=dword:00000001
"DeskTop"=dword:00000001
"AllUse"=dword:00000000
"DiskCheck"=dword:00000000
"Company"="Overflow"
"Program"="SCHOOLDAYS HQ"
"Version"="1.00"
"Script"="1.00"
"FullInstall"=dword:00000001