Some webpages are displayed incorrectly at first but if I refresh they're OK?
Sometimes when I load some webpages (can't remember any examples right now) they will display incorrectly and look weird. This happens on other browsers and on other computers too. If I reload it the webpage will look normal.
To describe what the sites look like, they look very basic, white background, default font, little design, buttons (which become only text) are stacked on top of each other when they should be next to each other, almost like a website looked like in the 90's.
Why does this happen? Can it be fixed?
try to clear the cache : Firefox button > Options > Advanced panel > Network tab > Cached Web Content > click Clear Now
Thank you, ideato. As far as I know the cache is where temporary files are stored, and I guess they aren't really important.
Sounds that CSS files get blocked if a reload works.
Which security software (firewall, anti-virus) do you have?
Make sure that you allow full internet access for Firefox and other browser if they have the same problem.
You can also try to reset (power off/on) the router.