You will need to uninstall and reinstall SilverLight and a new version of Firefox.
1. Go to Windows control panel
2. Uninstall Microsoft SilverLight
3. Go to the link: https://www.mozilla.org/en-US/firefox/organizations/all/
4. Click the link for Firefox 52 at center-right on the page
5. Select your language (e.g.: English (US)), click Download on the icon that matches your operating system (most often, this is Windows 32-bit)
6. Follow the automatic installation process on your workstation to install Firefox ESR
7. Log into Blackbaud Grantmaking
8. Silverlight Message comes up again
9. Install SilverLight from that window
Once Silverlight has reinstalled you will be able to access Blackbaud Grantmaking.