I have a eMachines netbook M350. It came with Windows 7 Starter installed. Recently, I reinstalled a fresh copy of Win 7 Ultimate, downloaded the wireless drivers from the manufacturer's page, and now I can't connect to any wireless network when the netbook is disconnected from AC power.
Sometimes, the wireless works fine after a reboot, but it's not always the case. Usually, it stays connected for 2-3 minutes, then it disconnects from the network.
Now, I don't think it's a hardware issue, because I booted it with Ubuntu on a USB drive and it works just fine, connected to AC power or not.
On the other hand, now I can't restore the netbook to the default installation, because when I reboot the computer it doesn't show me any option to do so. Does anyone knows how can I restore the system?