I don't know how much help this will be, but I found this link:
www.bullguard.com/foru...51940.html
If nothing else, the tool they mention, HijackThis" could be useful for you to in finding the culprit. I have found some cases recently where a computer's DNS settings were changed which makes it seem like the internet is down but it's not.
Check this:
Open a command prompt (Start, Run, cmd enter) and type ipconfig /all
Note what your DNS server(s) are and then ask your ISP if they are correct. If your DNS settings get hijacked by a malicious outfit, they can easily trick you into thinking you are on a real paypal or ebay or bank website when in fact you are on their site. They can then get your passwords etc.
So, my advice is to verify your DNS settings and try HijackThis as a way to rid the malware.