Security Warning in browser

Hello,

I am new to the forums but have a question and wanted to see if anyone could help.

I have a htc hd2 with gingerbread 2.3.1 on it. I am able to view the internet just fine except for certain websites. When I visit the website I get an security warning that states the following:

Security Warning
There are problems with the security certificate for this site.

This certificate is not from a trusted authority.

When I hit continue I get an error that states the following:
Data connectivity problem.
The server failed to communicate. Try again later.

The thing is, I am able to browse pretty much any site but there are certain sites like the one I am trying to access that gets this security certificate issue.

Can anyone lean me into the right direction please???

Thank you.