Reading back my post, I noticed that I badly explained my problem.
From my Win 7 PC, I try to map a shared drive, and to simplify the problem, let's say that the shared drive is on an XP system (in fact I cannot map any shared on any OS). I can map this shared drive from another XP system.
My problem is not to map some data on the Win 7 PC
Sorry for the misunderstanding.