It had been saying there was some kind of file error, but it no longer says that. Now the "OS installation assistant window" comes up. That is really strange, as I had been using Parallels desktop for a few years, with MS Windows, no problem. Now all of a sudden it doesn't let me in. I don't know what to do. I have not been able to access my MS Word or Corel Photo Paint. Can anyone help me? Thank you, Judy