Can anyone help with some issues I am having on my Lumia 720 after the WP 8.1 update?

[WPCentral Question]

Lumia 720 facing issues after the WP 8.1 update.

Hello guys,

I'm facing these issues after the Windows Phone 8.1 Developer Preview update (OS Version 8.10.14203.306).
1. Not able to open an app on tap of the notification.
2. Proximity Sensor has got completely screwed up. The phone lies flat when I receive a call and freezes occasionally.
3. Because of proximity sensor, glance screen doesn't work.
4. Some apps(Facebook beta) do not respond quickly.

What on earth are these guys upto? I would like to know if there's a stable version and can I downgrade my phone to that one?

Please provide some help.

Thanks.