I can not open my project in unity (this project only): here is the error message :
Corrupt window layout. Try deleting Library/WindowPreferences
Details : Failed to read window layout: there’s no main window on it !
a solution ?
on Windows Vista
thank you !
edit : everything is back to normal but it’s worrying because I dont know what happened!
Hey!
Just to be on the safe side you might want to start a new project so you don’t risk loosing a load of stuff, and backing it up too 
To start a new project, open the project and select everything in the project folder. Click Assets → export package and then save to a destination thats easy to find again. Next up, go to file → new project and make sure standard and pro are not selected!
Once your new project loads up, go to Assets → import package and select the file you saved earlier
hope that helps!