unable to sign-in to financial websites

So the computer recently became infected with all sorts of spyware, including spysheriff (I have a hijackthis log going in the other forum) and I'm not sure if this is related or not, but for some reason I'm not able to sign in to any financial related websites, like banking or credit card sites. I can sign in to e-mail, ebay, etc. just fine, but some of my banking websites don't even display the sign-in box, and some at least have the sign-in box but then take me to a blank page (I don't even get a "page cannot be displayed…"). I'm running Windows XP and the problem happens with both MSN and Inernet Explorer. I've been able to sign in to these sites from other computers so I know the problem doesn't lie with the websites. Any idea what's causing this? Is it something I should be concerned about?

I'm going to post this in the hijack log forum. Upon further review I'm not sure that this thread really belongs in this forum.