Does Symantec Web Gateway use SSL3.0?
Beginning with SWG 5.2.2, SWG no longer supports SSL3.0 protocol. For earlier versions of SWG, Symantec suggests discontinuing the practice of using SSL3.0.
To disable SSL 3.0 within Firefox settings, click Advanced Tab->Security-> uncheck Use SSL 3.0
To disable SSL 3.0 within Internet Options, click Advanced tab -> scroll down to Security->uncheck SSL 3.0