Update (11/28): Microsoft has acknowledged a random rebooting issue on Windows Phone 8 and has promised an over-the-air fix during December. It's yet unclear what's the source of the reboots and so far no clear pattern (or third party app) has been identified as such. Opinions around the web from WP8 phone owners seem mixed between those that have at least suffered once from this problem and others that are pretty vocal about the OS, saying their phones are rock solid and performing up to expectations.
Original story is below – as reported on November 21:
Multiple people are reporting problems with their brand new Windows Phone 8 devices. The two key issues seem to be email-sync problems and random phone reboots that are reportedly happening regardless of carrier choice, according to Mary Jo Foley from ZDNet.
Foley said she hadn't had any problems with her loaner HTC 8X until just the other day. The email client and Microsoft Account on the handset somehow went into an endless loop of trying to resync and the phone even spontaneously rebooted one morning.
A quick visit to Microsoft's support forums as well as the WPCentral forums revealed that other users were having similar issues. Some said that removing the Skype for Windows Phone 8 app would resolve the rebooting issue. It may or may not have helped but Foley still had to wipe and restore the smartphone to fix the resync problem.
The editor reached out to Microsoft about the issues and was told officially that the company is investigating reports of these incidents, leading one to conclude that it's not an isolated event. Skype conveniently had no comment on the issue, instead suggesting she direct all inquiries about it directly to Microsoft's Windows Phone team.
Keep in mind that this is only one person's account with a single handset but there are others complaining of similar problems. In fact, these same people were voicing concerns even before the Skype app was available so it's entirely possible that the app has nothing to do with it. We'll keep a close eye on this and update if anything more comes of it.