If you're experiencing problems with browsing, you could try to install another browser, e.g. Mozilla Firefox, or Google Chrome if the errors don't prevent you to download them... If they do, then you have to find an alternative way to get them to your computer. A friend with a pendrive? Or if you can accept email-attached files, I'm willing to send you a Firefox installer, we can exchange email address in private message.
You should also give a try to Microsoft's free antivirus software called "Microsoft Security Essentials"
If it's not updating automatically, can't you initiate the update process? Do you get any error messages, when it fails?