TROUBLE WITH INTERNET EXPLORER AMONG OTHER THINGS

Well I recently got a virus or something
thanks to your guy's help I managed to get rid of it, but ever since then I can browse the internet on FIREFOX, but when I try to upload say a picture on photobucket it says a network error happened. I've also try to connect to the Itunes store through itunes and it says to make sure I'm connected to the internet, which I am. Now that I tried to open up internet Explorer it wont even display any page. I ran the network diagnostics and this is what it said:
Windows cannot connect to the Internet using HTTP, HTTPS, or FTP. This is probably caused by firewall settings on this computer.
Check the firewall settings for the HTTP port (80), HTTPS port (433) and FTP port (21)
How could this have happened? I haven't messed with my firewall settings

Also when I try to update my antivirus software it also says a network problem happened and that I should un-install my software and install it again
Do you think that has to do with the same problem???

Thanks

You Using a Proxy Server?

Your going to have to excuse my lack of computer savyness
What is a proxy server