Wireless connectivity problem (and could it be spyware?)

The computer in question here is a laptop which is apparently connecting to the house’s wireless network – it is acquiring an IP and everything seems to be in order, except no actual internet access via any browser or if I try to ping a website. There are multiple other users accessing the wireless network with no problems, and this same computer has accessed the network in the past without problems. That is, on the face of it, the problem I’m attempting to resolve – a wireless connection that looks exactly like a wireless connection that is receiving a signal, transmitting a password, acquiring an address, and connecting, except once it does all that, there’s no access. The computer can’t access the router setup page, either. What could be causing that?

Now here’s the “what might have changed” part. We were watching a movie on the laptop last night, and it spontaneously rebooted, having downloaded a critical update (which, if I’m not nuts, means that last night it had internet access). At least, a little Windows update bubble popped up once the computer booted up, and said Windows installed a critical update that required rebooting. Since then, there’s been no internet access. Shutting the Windows firewall down temporarily didn’t change anything.

Part two: since then, there have also been those “shutting down X program” messages on shutdown. Several times the program being shut down was called Dummy. Once it was called B28. And a couple of times an error message popped up referencing a socket notification sink.

Does any of this, or all of this, add up to anything in particular? Isolated problems? My girlfriend (it’s her computer) says she has reason to believe that somebody could have screwed with her computer, and so the weird Dummy message and the lack of internet access point to something malicious having been installed. I’m loath to believe that’s what’s causing this particular kind of internet connection problem, but I’ll throw that out there as well in case that explains something. But hopefully there’s some kind of mechanical fix, or diagnostic method, that we can use to determine why exactly this computer is pretending to be all wirelessed up when it isn’t getting on the internet.

It could be that some bit of spyware (or maybe even something quite innocent) has knackered the Layered Service Provider (LSP) stack and that this hasn’t been remedied by removal of the software. Once you’re reasonably sure the machine is clean, try running LSPFix - from here:
http://cexx.org/lspfix.htm