A checksum error occurs when the values you entered for company name and location don't match the values expected by the setup program. For example, if your license email shows the Company name as "Dan's Software Emporium" and you type in "Dans Software Emporium", setup will detect the missing apostrophe in "Dans" and return a checksum error. If you pasted license information from your license email into the Setup dialogs, check to make sure you didn't inadvertently capture/paste any leading or trailing spaces. If you require assistance, please email us.