F5
From lurkmore wiki
F5 is a function key, one of usually 12 F(x) keys on the standard computer keyboard.
If an Internet page is not loading correctly, hit F5 and wait. If you give it some time and it still doesn't load correctly, hit F5 again and wait some more. If that doesn't do it for you, there's always tabbed browsing + F5. Unless you suck.