I have a buddy that just returned from a business trip where he connected to a DSL connection at a hotel. He connected via a line, not wirelessly, but didn't have to type in any sort of connection username or password in order to get access. Upon returning home, he discovered that his computer was connecting to his wireless connection, but some applications--namely IE, Firefox, or Outlook--are unable to connect to the internet. Other applications, such as Skype, have no problems connecting.

His wife went with him on the trip, connected in the same manner, and has had no problems upon return. They are both running Windows XP.

Has anyone run into this sort of issue before? And does anyone have suggestions towards a solution?

Check his connection settings to make sure he's not attempting to connect through a proxy.

Already checked. All his basic settings look spot on.

You said he uses IE... it could be some sort of spyware that forcibly installed itself.

Yeah, but it is effecting Firefox and Outlook, as well. That may indicated some sort of tampering with Microsoft's proxy server information, but I can't find any funny business.

Google's Desktop Search, for one, does some weird hokey in the OS kernel to intercept outbound TCP port 80 connections (such that it can insert Google Desktop results in Google Web searches). It's entirely conceivable that some other sort of evil application could be patching into the same hooks.

To try: telnet to port 80 of some web server by hand (or via a bland tool like wget or curl) and see if you can make that work. If it works, then blame the proxy settings. If it fails, then ponder the spyware and consider something as painful as reinstalling the system.

In the end, I had him grab his .pst file and roll back to before the problem occured. This fixed the problem, so fortunately no harm was done.