Itunes Cannot Download Anything

Ok, so after i got Internet Security 2012 installed, my iTunes started to behave strangely. First of all, it treated me as if I was new every time i launched it (but i fixed that problem, by re-installing iTunes), and the fact it won't download anything. The thing is, diagnostics show it is connecting to the internet, and I am able to browse the iTunes store. But when i go to download something, i get nothing for a minute or so, and then the download stops, because connection timed out. I have added iTunes to the application list, and made sure it had all the access it needs. And when I look at the internet activity, I can see data going out, but none coming in. I would also like to add that this was working when I had the 2011 version, and has stopped after 2012. Please help!