What's with my laptop Wi-Fi adapter?

It'll turn on one moment, then the next, it's non-existant and i can't connect to any Wi-Fi network. I've looked at the battery settings, but i can't find any Wi-Fi adapter disabled or anything. Why does it keep turning off. And normally, when it turns off, i'm forced to restart the laptop and hope that i can finish what i need in the few minutes before it turns off again. Any ideas?

Added (1). Okay, it's a lenovo thinkpad t400 with an intel adapter. Don't know how that helps. It's a laptop issue since it just changes. The reason i guess laptop because when it's working, and i pull up the wireless broadcasting window, i get bluetooth and Wi-Fi, but when my laptop refuses to connect to any Wi-Fi, and i pull up the wireless broadcasting window, i get bluetooth only, the Wi-Fi option is non-existent.

One idea would be to tell what laptop, what OS, what router, where both are when this happens, what surrounds them (metal objects, other radio wave controls). Then you might get some accurate guesses.