I have a Dell Precision M70 (yes - its old now but it was great when I got it, alright). Since I reinstalled the operating system I have experienced that the operating system is shutting down my wireless network card.
I knew that there were a setting for it somewhere - but I just couldn’t find it… Very frustrating. But here is how to do it in Vista:
Go Start->Computer and right-click and go Manage. This will open Computer Management. Select Devices and then Network Adapters and choose your network card, right-click and choose properties.
Now the following dialog appears and you can un-check the box that allows your operating system to shut-down the network-card.
Easy, wasn’t it ;)