Admin Panel - 'Edit' makes area to edit disappear!

Hey folks. First post here, but I've been lurking and soaking up the knowledge. I wasn't able to find anything in FAQ or search that was relevant to my issue - maybe someone will have an idea of what's happening here.

When using the Admin Panel, when I click the 'i' for info on a task or setting, it displays the description box on the right as normal.
However, when I select "Edit", the description box and any options it held disappear.
I have already checked version (1.3.9h), cleared my browser cache and relogged - still does the same thing.
This appears to happen for options of certain types - for some (like sorting where you place the number in the field) it appears to work fine, but for true/false options or anything with a 0/1/2/3 multiple choice switch it disappears.
Here's an example - Changing the product display sort order. The before is on top, with the info box. Once I hit edit, the bottom box shows as pictured and I cannot edit the setting.

[IMG]http://i.imgur.com/OiIGml.jpg[/IMG]

Any help offered is more than appreciated! I'm still working on getting everything configured and this is proving to be quite a setback.

Thanks!

report back any error logs in the folder please. > root directory/ cache

haredo:

report back any error logs in the folder please.

Didn't know that was there - thanks!

[24-Apr-2011 17:31:14] PHP Warning: call_user_func() expects parameter 1 to be a valid callback, function 'cfg_password_display' not found or invalid function name in :censored:/zcadmin/includes/functions/general.php on line 1701

[24-Apr-2011 17:31:14] PHP Fatal error: Call to undefined function cfg_select_option() in :censored:/zcadmin/configuration.php(179) : eval()'d code on line 1

Forgot to include this earlier: the first time I saw it happen was right after I put in my Paypal Express API parameters.

Please read this thread: > http://www.zen-cart.com/forum/showthread.php?t=164099