By the way, I have another last question:
I was going to format the HDD, but just ran ComboFix (I know that if something happens, I don't care, since I'm going to reinstall Windows anyway =P )
and at the same time Microsoft Security Essentials told me that he detected items that have not been yet classified for risks, and will send them: "C:\32788R22FWJFW/iexplore.exe"
Do you have any idea or opinion about it ?
By the way, if people have the same problem.
When your Network connection disappear... check your device manager, and chances are that you're going to see missing drivers for the network adapter... even if it was installed and working fine a couple of hours before!