Thank you for your answer.
Well i tryed what you said but it still doesnt work. I even try to uninstall and install again but it still doesnt work (i mean ie8) and avast not much.
Anyway, i m just using this windows vista (and i dont like this for many reasons) for office 2007.
Another reason to keep using Ubuntu linux... I doanload the virus database by myself (cuz it doesnt want to connect by itself) : there was a trojan... So maybe a virus program. I ll scan my vista harddrive under linux and i ll see...
But anyway thanks for your answers Black3agl3