I ran into this with my corporate e-mail this week on a Google I/O Evo. The setup of my exchange account was painless. Just need to plug-in my e-mail, password and a device password. Exchange syncing works fine until you turn off your phone. When you power the phone back on, it boots up to the point where the Sprint intro video plays. At that point, according to Sprint tech support, the Exchange syncing hits a snag and causes the phone to restart indefinitely...playing that same loud, annoying intro video over and over. The only workaround was to open up the bootloader (power+volume down on power up) and erase all my data. I went through a simple setup and a simple setup + exchange again to confirm that it was indeed the Exchange account that introduced the problem. Hopefully HTC can get this fixed soon.