Hey I finally got THE error message from my computer that helped me.
I had put the WinXP home disc in even though I have XP pro and it gave me a message :
" winlogon.exe ... File is absent or corrupted."
So i've put my BartPE disc in and extracted the winlogon.exe file in my c:\windows\system32 directory. Works fine, but the Network Cards don't work anymore. I have posted the problem on the Hardware section, so if anyone knows anything about my new problem, please HELP ME !