see this article that appeared since this post:http://www.olpcnews.com/forum/index.php?topic=4160.msg28018#msg28018End Edit
You have upgraded to 767 (8.2.0), I see. So, you can clear the network from Control Panel rather than removing the file "networks.cfg" (althought that may still work). Under the main page incon, there is menu choice of Control Panel. Within this graphic is Network. Network has in its graphic Wireless at top with Reset Network History -- this cleans out the "networks.cfg" file.
Whenever I have reinstalled my software (doing some other stuff), It seems like I always have to putz around to get the WEP connections and key saved. Here are some things I have to do to watch myself to be successful:
Wait until the MESH searches finish before trying to connect to the wireless.
Use upper case letters in key (for my Linksys WAP11). Watch that I do not type the letter O (never a letter O) instead of zero.
Pull down the menu choice 40hex/128bit. There are 26 numbers/letters in my key
Check Ok at bottom of popup window.
I am still unclear if I have to reboot after clearing the network history.
I generally clear history and reboot if a connection fails -- probably not necessary.
Sometimes I have to try several times ( maybe my entries) to get the key to stick -- once it sticks, it stays stuck.
If the connection is successful, you will see an entry in the file "networks.cfg". It will contain your key.