URGENT, project craches on start up

hi ,
project crashes on start up, please this is very urgent

link text

your log says “LogPackageName:Error: DoesPackageExist: DoesPackageExist FAILED: ‘None’ is not a standard unreal filename or a long path name. Reason: Path should start with a ‘/’” could yo check yoru project file path and name

i didn’t change anything in it , and i was working on it since weeks ,
i need help please i have to deliver the project tomorrow or ill be in big trouble ,

i was clicking the drop down menu in the Houdini asset to change materials from inside of it. then crashed and never open again

i don;t know if that has any link . and that happens while i was downloading AutomotiveMaterials from the marketplace. i don’t know …
i’m new to the unreal .