Firewall could be the problem, as could DNS server settings.

>>Hi Naomi,
>>
>>>Do you know what can I do and how can I fix the problem?
>>
>>check if someone modified the hosts file (C:\Windows\System32\drivers\etc\hosts) on your computer.
>>
>>Can you PING web sites? Can you ping an IP address?
>
>Hi Christof,
>
>After so much trouble and calling Customer Support I pressed on Windows Update button, installed latest updates and I'm Ok now and also with IE8. Though I did disable Comodo Firewall.
>
>Do you think Comodo Firewall could have been a culprit?
>
>Thanks a lot again for your help.