There are several reports of a major bug with Google Search in the Google Web Search Help that say people using desktop search but the interface looking as the tablet search interface.
The reports started to come in 5 days ago and more and more reports trickled in since. The first report said:
As of today, whenever I search through Google, I see the tablet-refined search results. When I switch to Incognito, it uses the standard search. I thought it might be an extension, so I disabled them all, and that did not fix the problem. I thought it might be my user agent string, but other sites are detecting it correctly (Chrome 18, OSX Lion). The url for a search term doesn't change based on a switch to incognito; ie searching "dogs" outside of incognito will show the exact same url as searching "dogs" inside an incognito window. Please help if you can, thanks. :)
Jacqueline from Google said:
Thanks for the reports, everyone! We're continuing to investigate the problem, but to help us assess the severity - are there tasks that you aren't able to accomplish while in this state?
If you see this, help out Google by submitted this information to Google at the thread.
Forum discussion at Google Web Search Help.