Run a projet

Hello everybody!
I cannot open a project with the launcher , or else.
This message appears:
"
The following errors occured:
-Cannot open an empty project. Addding a default empty scene

-Syntax eror at line 1:
Unrocognized attribute (<)
"

 The project size is almost 1,5 Go, not so empty as it's said.

Please help me if anyone knows how to open it,
thx a lot.
Sebastien