Adding a server certificate to IIS 7
When adding a site binding to IIS the following error occurs:

The solution is when importing the certificate to mark enable the option "Allow this certificate to be exported".

Links
References
Edit Site Binding
---------------------------
Edit Site Binding
---------------------------
There was an error while performing this operation.
Details:
A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520)---------------------------
OK
---------------------------