Thank you everyone !!!
In fact I already shut down all my programs and even my PC !!! I restarted it...
it still gives me the same error message ...

Does anyone know if that could have anything to do with a protection system, since I am working from my office. Could the network administrator of the comany have done some restrictions or not ???!

Meanwhile, and in all cases I will try Lori's suggestion !!!

Thanks a bunch !!!