Safari 4.1.3 will not open secure pages

[Anonymosity]

I am unable to get Safari 4.1.3 running on Mac OS 10.4.11 to open secure pages. It just gives an error message.
'Safari can’t open the page "https://<address of page>” because the server unexpectedly dropped the connection.'
OR
'Your browser sent a request that this server could not understand.
Reason: You're speaking plain HTTP to an SSL-enabled server port.'

Is there anything I can do about that?

UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; rv:1.9.2.23) Gecko Firefox/3.6.23

[Antony]

Is Safari 4.1.3 working normally?

Was it just some particular secure page or all secure pages?

UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.23) Gecko/20110920 AlexaToolbar/alxf-2.14 Firefox/3.6.23

[Anonymosity]

Is Safari 4.1.3 working normally?

Was it just some particular secure page or all secure pages?

Safari 4.1.3 works normally with http pages. It failed to load all the https pages I tried.

UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:7.0.1) Gecko/20100101 Firefox/7.0.1

[Antony]

Are those https webpage loadable by other browsers?

Did you touch/modify Keychain Access? (Or did you remove/block System Roots?)

Or do you have any application (e.g. anti virus, internet security) or router that blocks https connection or associated ports (usually port 443)?

UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.51.22 (KHTML, like Gecko) Version/5.1.1 Safari/534.51.22

[Anonymosity]

Are those https webpage loadable by other browsers?

Did you touch/modify Keychain Access? (Or did you remove/block System Roots?)

Or do you have any application (e.g. anti virus, internet security) or router that blocks https connection or associated ports (usually port 443)?

Firefox and Opera can open secure pages without any problem. I have never done anything to the keychain. I have not done anything recently to the operating system either. I have Clam antivirus, but it never blocked access to any sites. It only watches three directories for viruses being added to them. My other Mac is connected to the same router, and it has no problems with any Internet access.
How would I find out exactly what Safari is doing? I see only the Preferences to change settings and it says nothing about secure site settings.

UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; rv:1.9.2.23) Gecko Firefox/3.6.23

[Anonymosity]

This is strange! I just reinstalled Safari 4.1.3, and it now loads secure pages. I have no idea what happened, but the problem appears to be solved.

UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; rv:1.9.2.23) Gecko Firefox/3.6.23