I made a fresh install of Mythbuntu 10.10 64-bit and was on my way making things work. TV was duplicated and no sound but it is on its way... However, I tried to change to another theme to make it work more nicely with my old 4:3 LCD monitor. But after my change to that theme I cannot get in to the settings in the frontend or the backend. MythTV hangs. I can stop the freezing with ESC and choose another menu-item. But as soon as I try to enter the Settings Menu it freezes again.

Is there a way to change the theme via command line or is there another way to solve this problem? Except reinstalling everything...

My hardware is:
AMD 64
TV: Sundtek Media TV pro USB stick (use the analog reciever)
Graphics: ATI Sapphire HD 4550

All kinds of ideas and suggestions are very appreciated.