UPDATE!!I left the stuff below in case anyone already read it, or maybe so someone can help me find the flaws in my logic. Anyway, upon closer inspection, this doesn't work very well at all. Yes, it keeps the display name box from appearing in the edit profile screen.... but if the user tries to make any other changes, it chokes - it expects to find a value there...... I think if I can just tell it somehow to use the value from the username box, I'll be off to the races..... but I'm too tired now to work that one out. I'll check here tomorrow before I devote any more brainpower to it. Thanks, and sorry for the false alert

tykatt~
WHAT FOLLOWS IS MY BROKEN MOD.... for educational purposes only!!
well, wonders never cease.... I started tinkering, and I managed to modify this without breaking my board (so far - *heh*)...... If anyone else wants to disallow users to change their display names in the profile settings..... here's how I did it....
This mod was done on my clean install of YaBBSE 1.3.0
Open up sources/Profile.php... and find this (in mine, it started at line 126):
Quote <td width="45%"><font size=2><b>$txt[68]: </b></font><BR>
<font size=1>$txt[518]</font></td>
<td><input type="text" name="name" size="30" value="$memsettings[realName]"></td>
</tr><tr>
If you don't ever want it back, you can delete it, but I'm always reluctant to do that, so I chose to remark it out instead. Below is what I pasted in its stead. If you ever want to restore the ability to change display names, all you need to do is remove the top and bottom lines, and change all the {} to <>.
Quote<!-- The following lines remarked out to disallow users resetting display names
{td width="45%"}{font size=2}{b}$txt[68]: {/b}{/font}{BR}
{font size=1}$txt[518]{/font}{/td}
{td}{input type="text" name="name" size="30" value="$memsettings[realName]"}{/td}
{/tr}{tr}
-->
DISCLAIMER - I'm not a modder, or even all that familiar with php.... please back up your Profile.php file before trying this, as I cannot be held responsible if you toast your board.
PS - if anyone knows a better way to accomplish this, don't be shy about correcting me

tykatt~