The error is most likely because of the way your individual computer (not server) is set up.
Your browser has a small setting that may have been changed accidentally, by malware, or by an update.
Here is how to FIX your internet connection so that it wont show that error in wordpress for themes or plugins… I JUST did this an KNOW it works, assuming its your problem like it was mine.
I pulled these instructions off the internet to fix an internet connection that appears to be on a proxy )even though it is not).
Go into firefox (or IE if you don’t have firefox) — You do not need to do this for every browser- just once in one of them:
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Firefox
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Step 1
Launch Mozilla Firefox on your computer. Click “Tools,” click “Options” and choose “Options from the menu that slides out.
Step 2
Click the “Advanced” tab in the Options window. Click the “Settings” button in the Connection box.
Step 3
Locate the selected connection option in the list on the Connection tab. If your Internet connection uses no proxy server, the “No Proxy” connection setting option is enabled. If either the “Use System Proxy Settings” or “Manual Proxy Configuration” setting is selected, then your computer accesses the Internet via a proxy server.
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Internet Explorer
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Step 1
Open Internet Explorer.
Step 2
Click the “Tools” drop-down arrow in the upper-right portion of the browser window. Select “Internet Options.”
Step 3
Click the “Connections” tab in the Internet Options window. Click the “LAN Settings” button. If there is a check mark in the box next to the “Us a proxy server for your LAN” option, then your PC accesses the Web through a proxy server. If there is no check mark in the box, your computer does not use a proxy server.