serious browser problems. please help.

Hi, everytime I log on to the internet, it says I logged on but my browser doesnt work for any sites. All the sites say "page cannot be found" as if you're not logged on but when i check my tool bar, it says I'm connected. There never used to be a problem with the internet before so the problem shouldn't be from the settings. I used to solve this problem by using "system restore" (in Windows XP) but it doesn't help anymore. Does anyone know how to fix this? I tried troubleshooting from the instructions given by the computer but it doesnt list my situation. Can someone please help me?

PS. I use a free internet sevice and I'm using "Internet Explorer" as my browser.

haveyoutried a diferent browser or conecting to a program that uses the internet (e.g msn mesenger)?
also, insert your xp cd (if you have one), click start>run and type sfc /scannow note the space after the "sfc" also, do youhave a firewal that may be causing this problem by blocking I.E from conecting to the intenet?
also, what isp are you using? have you got the latest microsoft updates?

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