Class Management

[pinnacle_man]

hi
I am building a class model.  I have got 35 classes with attributes and operations (you can think how big the class model look like:-)
I tidy up the class model and save it.  
When I reload the project it lost all tidiness and I lost my two hours work of tidiness.
Did any one experience the same thing?
Is there any solution for this?
Thank you