Mystery: my primary computer (Windows 8) appears to access 3 particular websites, but displays the content as blank pages
All 3 websites display content properly on my other home computer (Windows 7). Both computers access internet through my cable internet connection.
My primary computer accesses & displays all other websites properly (of dozens that I've checked).
The blank page problem occurs on primary computer using any of the 3 web browsers that I used.
The 3 problem websites display properly on my primary computer IF connecting via a proxy server, using program CyberGhost.
I thought maybe my firewall program is erroneously blocking content from the 3 problem websites. However, I've reviewed the firewall parameters & they don't exclude those websites. Also, I think the firewall would not display a blank page if you tried to go to a blocked URL. Instead, I think it would give you a message "access to this website is blocked" or similar.
I should mention that there is no reason for any of the websites to block me. I last posted (routine post, nothing controversial) on one of the 3 websites over 7 years ago & have had regular access to their content since then until about 2 days ago. I've never posted on the other two websites.
Of course, if I suddenly became persona non grata at a website, it would block my access with some message and not simply display a blank page.
Any ideas on what could cause this & how it can be fixed would be gratefully appreciated.
Life is short, be nice to people.