Internet Explorer cannot display the webpage

Hi,

I usually use Firefox but today I used my IE7 and recieved this message:
"Internet Explorer cannot display the webpage"

The webpage worked fine on Firefox but on IE7 it doesn't, I checked Internet Connection, Proxy and addons. everything seems fine.

Then I looked in Services and found that I have 2 IE7 opened instead of just one. I suspect that I have some kind of Trojan virus that is using my IE is there any viruses out there that can do it? if so how can I remove it?

Thanks

Daniel