I'm having a wierd problem. When I access a random website for the first time, I sometimes get a "Server not found" message. If I press F5, the site loads just fine. The second time I try to access a site it works without problems. Sometimes, a page loads, but assets on another server (css, js) don't. But after refreshing, those come back, too.
It just started this morning, and I didn't change any configuration or install anything. It happens with any browser (tested Firefox and IE), and I am running Windows 8.1. What could it be?