At some point over the last couple weeks I lost the ability to download zip and exe files from either IE or Netscape. I've tried clicking, right-clicking to "Save Target As", and opening in a New Window. The first two options create a very quick flash of a dialog box and then do absolutely nothing. It's as if I didn't even click on the link. The third option opens a new window with the proper URL in the address bar, but nothing on the page. The status bar at the bottom left says "Done."
So far as I know, I have no virus software running, and I've reset my Internet options back to the defaults with Medium security. By the way, this is for my home machine which isn't behind any firewalls.