There's probably nothing wrong with your PC. Some (especially)
foreign language sites does not have the proper meta tags to "tell"
your browser which language should be displayed.
In some cases where websites uses a CSS to define these variables,
your browser would not "reset" to it's earlier settings.
These are two probable reasons, but it's best you look at the HTML
headers to see if it is the case.
Eitherway, it is seldom due to your browser.