Problem with Rom Manager

[The Sapient]

I recently used Unrevoked to root my Evo. I then installed Rom Manager and tried to backup my phone. I open Rom Manager, click "Backup Current Rom" and accept the default name. My phone them attempts to restart, and gets stuck on the bootup screen (white with the words htc EVO 4G). I can get the phone running by removing the battery. But I must be doing something wrong. Any advice?