WOW!!!! I seem to have found a BIG oversight here...
if you add a custom text field, there is no limit to the number of characters that can be added...
in other words, in the display screen, a person can have 300 lines of text added...
I think you need to add a maxlength stat in the field settings...
(the current "size" of the field is set to 50, but that should probably be the same size as "maxlength", especially if you make it into a settable variable.)
for the moment, I have change the field size and maxlength (in my set up) to 25...
If anyone else is interested in 'fixing" this:
line 31 in CustomProfile.php
<td><b>' . $modSettings['CP' . $i . '_name'] . ': </b>' , !empty($modSettings['CP' . $i . '_desc']) ? '<div class="smalltext">' . $modSettings['CP' . $i . '_desc'] . '</div>' : '' , '</td><td><input type="text" name="default_options[' . $modSettings['CP' . $i . '_id'] . ']" size="25" maxlength="25" value="', @$context['member']['options'][$modSettings['CP' . $i . '_id']], '" /></td>