Applications can no longer open a push notification channel to my phone. Third party apps like AlphaJax, Smart Tile, and Pro Sports Scores give an error message when I choose to turn on notifications. I also cannot go to the Windows Live Mobile Device site and choose Ring It or Map It. That tells me there's a temporary problem with push notification services and offers to use text messages. Those messages work, but the problem is clearly not temporary as I've restarted many times over a couple weeks. Removing programs does not make a difference, either. I uninstalled everything that sent notifications other than the few that were still working and it did nothing.
This is the second time this problem has occurred. The first time was about a month after getting the phone and it was solved temporarily by a hard reset. I don't think it's acceptable to have to hard reset your phone every couple of months, especially when there's no way to back up text messages, settings, and application data. The phone is billed as a great gaming platform, but what kind of gaming platform forces you to lose all the progress you've made in all your games every couple of months when a basic feature of the phone stops working? There needs to be a service to manage push notifications on the device or internet side.
I'm a MCITP in Server Engineering and a Microsoft Certfied Trainer with 15 years experience in the IT industry. I'd be happy to lend my skills to troubleshooting the issue if anyone from Microsoft needs a pair of eye on the device side. I just will not perform another hard reset until there's an easy way to back up the apps and data on the phone. I also cannot recommend the phone to any of the businesses I consult for or to their employees whom I teach.
Also, don't forget the lack of Live Tiles updating at all. Recently, I reinstalled Flixster and moTweets. Both Live Tiles did not work. Not until I performed the steps outlined here, did my problem go away. Of course, this requires a Dev Unlocked phone (which I do) and isn't a supported method, and the average user isn't going to attempt this workaround. However, it does bring to light that there are certainly bugs within WP7, even with v 7.0.7390.0 (aka NoDo) that have gone unresolved.
With more and more apps being published, and more developers using the Live Tiles feature, the Windows Phone team needs to be working on fixing this issue (among others as well.)