''When you boot into safe mode, can you look at the device manager and see if Windows has detected the virtual NIC and installed a driver for it?''
Yes it does. Right now I tought to use Safe Mode with Networking to see if the Internet really works or not, but it forces me to activate before, so I can only use Safe Mode without networking. I don't know how to verify Internet connection.
''Have you tried bridged networking rather than NAT?''
I cannot do this because I use a USB adapter to get Wi-Fi, and I must install a program. I tried installing the program in a working XP virtual machine and I cannot install this program.
''There's some weird virtual USB activity in the log, and it looks like you have a USB network adapter on the host. Can you remove the virtual USB controller from the guest temporarily, to make sure that isn't causing some problems?''
No I can't remove the USB because if i do, I will not have acess to Internet. I'm not sure if you meant removing the USB physically (from the PC) or just from the guest VM.