From
http://forum.osdev.org/viewtopic.php?f=8&t=677:
Quote:
I belong to the wiki usergroup but can not log into the wiki.
The software that controls the wiki is more restrictive about characters used in usernames. If you have spaces, underscores, or other special characters it will be required to edit your username. You can can your username in the User Control Panel -> Profile -> Edit account settings, ucp.php?i=profile&mode=reg_details.
EDIT: whoops, didn't see that is was in the right forum (or it got moved?). But still, answer was right in the sticky.