I keep losing my assembly when I try to rotate it with the mouse wheel. It was shortly after saving the assembly when I went to rotate it and as soon as I clicked the mouse wheel to rotate the assembly disappeared. I have tried the "F" key with no luck. if you close it down and open the file it will bring it up but as soon as the wheel is used it vanishes. I have even tried to use the view orientation button, with that when you click on it, it does not bring down the option to choose a pane it defaults to a view on the right but will not refresh the assembly. It is vary frustrating due to the time I spent on the parts. Any suggestions would be great I do not want to rebuild it again.