I want to share my experience with 8.1 and XPS 10. I installed 8.1 and everything was working fine for several days. I even had an SD card installed the entire time. Today, after booting up, I removed the tablet from the dock and checked for updates. I almost always keep the device docked, but I was riding my exercise bike, so the dock was not helpful. I installed 6 updates and when it rebooted it took me to the Dell Logo screen this topic is discussing. My research led me here. No matter what I tried I could not get the darn thing to boot up properly. I was looking in to the USB boot disk but had not tried that yet. I put the device back in the dock and turned it off. The next time I turned it on it booted up perfectly and the updates had been installed as well. I rebooted the device and it worked perfectly again. I shut down the device, removed it from the dock, and turned it back on. It stopped at the Dell Logo screen and would not go any further. I turned it off again, put it back in the dock and turned it on. It booted up perfectly.
My answer is to only turn the device while it is in the dock. Not a very good solution, but that is what is working.
My XPS is now back at Dell for repair. I spent hours looking at the Dell screen and finally gave up. It shipped out Fed Ex today. Hoping to have it back next week.