Here's the debug_log.txt data when I click on the Tags tab:

zp_getCookie(dynamic_locale): SESSION[]=, COOKIE=
zp_getCookie(zenphoto_auth): SESSION[]=, COOKIE=
Backtrace: checkAuthorization()
checkAuthorization called
from require_once (auth_zp.php [40])
from require_once (classes.php [12])
from require_once (class-load.php [7])
from require_once (template-functions.php [13])
from admin-tags.php [7]
checkAuthorization: admins => (
1 => ( user => admin, pass => 1fb0e331c05a52d5eb847d6fc018320d, name => Admin,
email => webmaster@hidden.org, rights => 79710, id => 1 ),
)
zp_setCookie(zenphoto_auth, , 1246105591, /tools/zenphoto)::album_session=1
zp_handle_password: $authType=zp_gallery_auth; $check_auth=083149e7e3e9074e3115a0d966428212; $check_user=hgigallery;
zp_getCookie(zp_gallery_auth): SESSION[]=, COOKIE=
zp_getCookie(dynamic_locale): SESSION[khlc309mmhgjp2k34hl7lcj364]=, COOKIE=
zp_getCookie(zenphoto_auth): SESSION[khlc309mmhgjp2k34hl7lcj364]=1fb0e331c05a52d5eb847d6fc018320d, COOKIE=
Backtrace: checkAuthorization(1fb0e331c05a52d5eb847d6fc018320d)
checkAuthorization called
from require_once (auth_zp.php [40])
from require_once (classes.php [12])
from require_once (class-load.php [7])
from require_once (admin-functions.php [18])
from admin.php [11]
checkAuthorization: admins => (
1 => ( user => admin, pass => 1fb0e331c05a52d5eb847d6fc018320d, name => Admin,
email => webmaster@hidden.org, rights => 79710, id => 1 ),
)
checkAuthorization: checking: 1
checkAuthorization: match

Please let me know if you need any more info?

Thanks. Have found the problem. Fix will be in tonight's nightly build.

Wonderful. You guys are awesome!

would it be possible to post the adjustments that need to be made - I just upgraded to 1.2.5 (in hopes that this issue would be solved), and it would be wonderful if I could just update the particular files that need to be updated instead of going through the whole process again...
thank you so much for fixing this!

http://www.zenphoto.org/trac/changeset?new=4157@%2F&old=4156@%2F

However please note that there has been NO testing of this change applied to the base 1.2.5 release. Generally speaking, we never recommend applying a change in isolation of the development stream upon which it was developed.