My computer wont load pages

Hello,
My computer won't load certain pages, it started with hotmail, now facebook and msn home too, also when i click on links in some websites it does nothing
i am at my wits end if i have to send the puter to the shop again and spend more money just for them to re format the whole darn thing!
please has anyone got any ideas for me? i have tried everything i know how to do and nothing has worked, it just seems to be getting worse!