SSL connection fails to authenticate certificates for some pages?

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http://askubuntu.com – This time, i am going to solve some irritating things with my networking on school, using ubuntu 12.10. I am perfectly able to connect to the proxy authenticated network the school uses. But my problem is something else; I am not able to access for example gmail.com or any ssl secured log-in pages. And where i am able to, i am not able to see any of the layout (f.ex. facebook) because the secure content is blocked. The thing is, i am able to connect to all those pages at home, but i am not able on the school proxy. So, could it be the proxy blocking the ssl connections, or the ssl certifica (HowTos)