So I've noticed that if the wireless is turned on for my 3DS it crashes after about 20 seconds, anyone have any suggestions for what I can do.

Well, this has never ever happened to me before. What game cart do you have inside of it?

Try going into your Internet settings and deleting all profiles (including original DS profiles), then re-creating the ones you need one by one. Try removing the game card and SD card. If it still crashes, try removing the battery and connecting it to AC. This one might sound random, but check both your 3DS's and your router's clocks, and make sure they're within an hour. (I have had really strange things happen with various devices when the year was different than the router.)

Oooh, this is what happened to my 3DS. I wasn't sure what to do, so I sent it in to Nintendo. You might want to do that if it's still under warranty.

Never got a warranty, even if I did get it it would be expired.

Oddly today I turned the wireless on after I turned on the 3DS it didn't crash but despite this Spot Pass didn't seem to work.

As I mentioned, try deleting the networks and creating them again.

Already tried that.

Okay so now after 20 seconds my 3DS is connected to Wi-Fi I get a message telling me my wireless has been switched off, in fact now I can't seem to switch it off.

EDIT: Now its crashing if I just leave the wireless on again.

Hmm, I hate suggesting this, but try a full factory reset. I believe it's the very last option in the settings and says something about formatting. Make sure to remove the SD card first and that there's nothing you care about on the internal memory.

If that doesn't work, you may have to buy a new one.

Yeah there's no way I'm gonna resort to buying a new one or resetting the memory so I can loose all my games and, I can't afford a new one.

I'll just have to wait this out, I'm really mad now though because now I can't trade pokemon and this makes my regular DS useless, when X and Y comes out then I'll get a new 3DS.

I'll try calling Nintendo tomorrow to see if I can possibly pay to get it repaired since I don't have a warranty.

Ooh, right. I think it's $75 for a system out of warranty, but I might be wrong.

Have you tried googling what to do sometimes you can find out what to do

Yeah that was the first thing I did, Google never helps when it comes to specific issues like this.

It's now been more then a week and now I've stopped getting the crashes with the wireless on again, so it just some how stopped.