On the client machine:
- Win+R, MMC, Enter.
- File, Add-Remove snap-in, Certificates, Add, Manage certificates for: my user account, Finish, OK.
- Navigate to "Certificates - current user / Trusted Root Certification Authorities / Certificates".
- Right-click on Certificates container, All tasks / Import
- Choose your .CER file you've transferred from the server machine.
- On the next screen, choose "Place all certificates in the following store", click "Browse", check "Show physical stores", then choose "Trusted Root Certification Authorities / Local Computer".
- Press "Finish" finally.
- In Internet Explorer: Tools - Delete browsing History,
- In Internet Explorer: Tools - Internet options - "Content" tab - Clear SSL state button.