Modifying custom prefs (Manila) causes error

[Chris Bunch]

I am trying to modify custom prefs to get a more relevant signup information
from new members to a particular site.

If I do this, then attempts to load the sitename/member/signup page produce
this error:

Sorry! There was an error: Can?t get the ?type? attribute because the table
doesn?t an attribute with that name.

I have tested (with xml.compile) that the replacement text in custom prefs
is good xml.

All is well again if I restore the defaults to custom prefs.

I have access to my server: can anyone suggest where I should look?

I am also having difficulty locating documentation on how the custom prefs
system works 'under the hood'. Does anyone have any pointers?

I am using Frontier 9 on Mac OS X 10.1.5.

Any help appreciated