authenticity... could not be verified ??

For various sites, now and then, i get this firefox error msg, or something like it...

*Cannot communicate securely with peer: no common encryption algorithm(s). Error code: SSL_ERROR_NO_CYPHER_OVERLAP

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.*

Any thoughts about clearing that up. Anything I can do on my end to facilitate?