Been having problems accessing google and the like? Ending up with strange websites instead? You've been hijacked.
I was hit by this and I'm seriously careful about viruses. No antivirus / spyware scans found the problem either. My dad's PC went down to it yesterday as well, so I suspect its effects are on the rise.
So if you happen to see any of the names: jupk.com, intercage.com and xeex.net on the status bar as the web pages are hijacked, try the following (I wrote it for my dad on a winXP system, so its a little on the "you know nothing" side of things):
Click on "Start" then "Control Panel" (you might need to go through "My computer" or maybe not)
There should be an item in there called "Network connections": double-click that.
That should open a window that has "Local area connection" in it. RIGHT click on that and
select the option "Properties". Within that list, double-click on the item "TCP/IP"
If you've followed all that, you are now on a window called "Internet Protocol Properties"
If you have the problem I think you have, you will see the option "Use the following DNS server address"
selected and some longish numbers in the two boxes below it (both starting with 8).
If you do, then click on "Obtain DNS server address automatically" instead. The two numbers
should then grey-out. The press OK and you should be up-and-running again.
You might need to clean out your cache(s) too.