I've got the same problem over here. I have Pranab Dahr's excellent safe mode patch installed for the rest of the system, but it doesn't seem to "load" in the CB interface. I am a novice at this with Joomla and CB, but think they are killer apps and are really sad right now not beeing able to install all the awesome plug-ins there are.
Any help in this matter is highly appreciated. CB seems to be the absolutley best way to make the users interact with one and other and I'm really psyched to get it implemented in my site.
Configuration
Joomla 1.0.7
Safe mode patch for Joomla 1.0.7 beta
CB 1.0 RC2
Safe mode: ON