Sorry you are having problems. Since this is a Beta release, I would suggest that you consider going back to the previous full release (3.51).
Alternatively, if you are interested in spending time to work with us to resolve the problem, it would be helpful if you gave us more information. For example:
1) Did you clear setup as recommended after the update ? If not, do so.
2) What was your previous version ? If it was not 3.51, install 3.51 and then re-install 4.0.
3) What is the exact sequence of events from power-up to the freeze you mention ?