Ran into a strange problem with Windows 8 Pro. Last night i installed Windows 8 Pro as an upgrade on a Sony Vaio laptop that had Windows 7 Pro on it. The install seemed to go okay. Then once installed, live tiles seem to work, native/Metro apps will start okay, but pretty soon after going into an app or settings, the screen flashes a few times and we're back to the lock screen. Signing in appears to do a full login. I've tried this with a local account and with a live.com account.

This is someone else's laptop, so we decided to let it breathe, in case the install was still settling in. Well, they say today it's doing the same thing. Open the music app, and within a minute it's back to signon/lock screen. However, they can go to the actual Desktop and run Zune to play music, and it seems happy.

In the past, i've installed retail Windows 8 Pro clean on a homebrew system, as an upgrade on a Dell laptop with a zillion apps and drivers, neither with any problems. Also, i've had the consumer preview and release candidate installed as well, no problems.

Any ideas on what's going on here?