Well, I'm not sure if my NDS Lite is still under warranty(though I'm beginning to think that there wasn't), but I can tell you that my problem is more in the physical aspect and not the "virtual" aspect. You know how the DS Lite works right. The bottom part connects the top part with two little side things that hold the middle section with the mic in. Well, the right side of that(the one with the power monitor thingy) happened to have literally broke off. In other words, the hinge is broken to the point where I'm forced to buy a new one.
However, I bought a protective case that basically uses it's own hinge thing to work with the DS Lite. I'm currently using this in the mean time while I work out a way to get a job to purchase a new DS Lite. Now, I have of course dropped the DS Lite a few times, and that part of the hinge was "drooping" a little and was cracked so I'm guessing that it breaking off was inevitable from the get go. And I've had that thing since it came out last June, so I've had it for a solid year.
In other words, your lucky to be able to receive another DS Lite as opposed to the situation I'm in. The time it takes to get and get back also happens to be in the effect of where you live in proportion to the location of the place you send it too. If the city that you send it too isn't that far from the city/town you live in, expect it in a reasonably short period of time.
People send in their consoles to be repaired all the time. Microsoft probably gets "dead" Xbox360's on a daily basis due to its unstability, or so I've heard.
Don't worry, you'll get it back in due time. It ain't fun to wait, but stuff like this does happen.
~C_L~