I have a rather curious problem, and with extensive Googling I can't for the life of me find someone else having the same issue.
I am putting this in the Windows 10 section because I recently took advantage of the freww upgrade offer, but I have been having this problem since I had Windows 7.
What will happen is certain websites will not load... but not all websites. For example, let's say I type into the browser bar the address for Facebook, and it loads just fine. Then while I still have the Facebook tab open, I'll type in the address for Craigslist and it will not load. No amount of refreshing will make it load, either. Then I'll try another website, say Google, and it loads fine. Then I try another website, say eBay, and it won't load. If I wait some time and forget about those tabs and come back, they eventually will load no problem.
I know what you're thinking, maybe the sites are just down at that time. I thought that at first too, until it began recurring with frequency on popular websites that are unlikely to be down. Furthermore, if I try to visit those websites that are refusing to load with my cellphone, tablet, or other computer, they will load fine. So I know the problem is with my computer. This happens randomly to different websites with no apparent rhyme or reason. It has been going on for months. It is not localized to one browser, as Firefox, Chrome, and Explorer all have the same behaviour, although my primary browser is Firefox.
I have run the most recent version of Malwarebytes several times with no success in finding or repairing the issue.