I have an old macbook pro os6.8. suddenly it will not connect to yahoo main site?

Only one page on the entire Internet stopped working for you?

Then ask the owner of that page.

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I have already pointed out that 10.6.8 no longer supports today's encryption, and that you need to upgrade to at least 10.10 Yosemite to use the Internet in a meaningful way..

Please describe your computer in detail as found under "About This Mac" and give and error messages you are seeing.

Have you made any system changes prior to your current problem?

Even the main page for Yahoo.com now uses encryption.

The encryption for Macs before 10.10 Yosemite or 10.11 El Capitan is too old to work with modern encrypted web sites.