Thanks for the explanation!
I think I misunderstood things before. I thought that SD-revovery+hard reset would restore pretty much everything to its original state, while the disable-packages you flash via usb only undo certain changes.
I am pretty sure that I did remove all the packages via USB at some point and flashing with your minimal-root still resulted in Opening Book Screen freezes. However. Once I have time, I'll try all disabling/recovery/reset procedures and rerooting with your minimal-root. It definitely seems more advanced. If it still don't work I might cry for help again.