Andy Beal pinged me about Google Forcing Desktop Download? Well, it is unintentional, what is happening is if you do a search for anything at Google and try to click on page two or anything in that navigational results bar at the bottom, it won't let you, in Internet Explorer. Andy explains that "Google has a transparent DIV tag that is interfering with the layer behind it. The problem doesn't effect Mozilla." Give it a try yourself, and if it is working, trust me it wasn't. Andy also has images of this.
So I went to our forums to post it and found a thread on it already named Googles' New Desktop Search Ad on SERPs - prevents Clicking SERPs Page Links. You would think they would test it out on IE before going live with the ad. :)
Forum discussion is also widespread; see Search Engine Roundtable Forums or WebmasterWorld.