[WIN7] Issue with viewing websites on PC

Not sure if this is the correct sub for my problem, but I'm having trouble accessing specific websites on my PC. I have tried multiple browsers so I do not think the problem is browser specific. Some sites work fine (eg. reddit, youtube) whereas some can be broken or impossible to access (eg. imgur, a wikia).

[Here](http://puu.sh/haII0/67efc5446e.png) is an example of the site being unaccessible, and [here](http://puu.sh/haISE/cc78fbf090.png) is an example of the site having what appears to be broken HTML. Does anyone have any idea what could be causing this? All help appreciated.