Big bug with Internet browsing

Hello,

for several days, I have big problems with internet browsing (I use Firefox, but the problem is the same if I make the test with IE).
At first I thought it was my connection was a problem, but no, I explain:
I have a tuned, I can call with watching TV on adslTV, chat on MSN, all this without problem, and at the same time I can hardly surf with firefox ... pages appear to half (when they appear), and again I am compelled to update continuously for the entire page is loaded.

Do you know this? Why it hapens ?

I do not know if it's a bug because sometimes also my firewall asks me if I allow access to an IP address (which has to do with no program).
The most strange is that no virus scan, anti-spyware company and does not detect anything, and the second home computer, surfing is going smoothly.

Think you can help me fix the problem?
Thank you!

in the various search engines available for your browsers (Firefox, you see by clicking on the G google search in default on the bar), you see that the intruder is that you have not installed.

Or different search bar with IE

Yes, a 99% chance that this is a malware related to the search bar. Sometimes you find software for turning, sometimes, antivirus, sometimes still in hand

Reboot the freebox.
If you still have worries.
Met XP SP3 if you're under this OS is also the part of drivers of your motherboard and your network card.