Crashntrash is exactly right. Ground speed means nothing.

Let's say your plane has a stall speed of 30 mph - that is, it needs to be moving THROUGH THE AIR at 30 mph in order to keep from stalling.

If you have a 15mph tail wind, you start your takeoff roll and the wind will help to push the plane along - giving you a faster GROUND speed.

Now lets say to took off at 46mph (Ground Speed) 46 minus the 15mph tail wind is only 31mph or 1mph faster than your stall speed.

Now if you climb too quickly, you will loose speed and drop below stall speed - or - if the wind picks up with a small gust, that will do the same thing.

Either way, I totally agree that the reason you crashed is that you stalled - IE, even though your plane was moving fast in your eyes, it was not moving fast enough THROUGH THE AIR to keep flying