Given the fact that you were able to create a new sde geodatabase and import the same data into it and interact with the data in the versioned environment, I will mark this incident as resolved.
A lot of my maps were using the maplex extension for labelling.
We just upgraded to 10.1 and everytime I open a map that had maplex turned on the mxd crashes.
If I get to the pause button ontime I can switch the properties back to the standard label engine, but it's getting rather frustrating.
Any fixes for this?