Hey there mate,
I too have a Wifi connector, so I think I can help out a bit.
The error is most likely to be caused by the following errors:
1) the anti-virus/firewall settings
2) Faulty network configurations
3) other
To fix this, do the following:
1) Know that the connector has some trouble with some anti virus programs and firewalls. This is the most easy to fix problem. First, if you have your anti-virus, locate the button/form where you can change the allowed programs on the computer. (For expamle, AVG has the exceptions button under advanced settings) If the file NintendoWFCconfig.exe isnt here (something like that), then find the locations where you installed the wifi files. Add the all the .exe files if needed. Firewall is just the same. Allow the connection if asked. If its asked, say: handle as trusted application. If not, find it manually, the same way as the antivirus. (NOTE: Zonealarm is incompatible with Wifi. Removing does not help. you will have to do a total anti ZA scan).
2)Faulty network is sometimes the error causer. Go to network connections, and see if a 2nd or 3rd connection is there. you will most likely recognize the connection directly.If you have a network bridge, add this connection to the bridge. (this is advanced, most likely you will not have this).Enable if needed, add to trusted connections if needed.
3) other: Other factors that can cause:
If you have let your DS fall a few times, then you can add it up I guess
Connector isnt properly attached.
Something is disturbing the signal
Re-install
If windows 7, let it run as admin, then if that not works, run as WinXp.
Guess this will do for a while, questions? PM ME.
Bokky out.