Admin login suddenly stopped working a week ago

Me too..
I updated Zen Cart ver. 1.3.9h about 6 months ago. I had been using v1.3.8a for more than a year, when my hosting service updated their PHP version, which disabled my shopping cart. The new version installed perfectly, and has been (seems to be) working fine except at some point within the past month my admin login stopped working. I have made no changes to my hosting service, or cart installation since the the update, except for adding products and configuring the shipping module in mid-October. I implemented the recommended security precautions (changed admin, reset permissions, etc. ).

My last routine Admin login was the first week of December, when I logged in without a problem. The next time I tried to login was a few days ago (Dec 13th), and discovered my login wasn't working. My hosting service claims that nothing has changed on their end that could affect my login (I thought I'd give that a second try).

I do use a custom template, but I use the overide system.
I've had SSL for more than a year (disabled it from the admin, to see if it helped my loging problem - it did not)
I read as many forum posts as I could fine. I did the Admin login reset via phpMyAdmin, per the wiki instructions. I can see the "new" Admin user in SQL. However, I get the same login error message when I tried the newly reset Admin login.
I emptied the browser cache, deleted passwords, history, etc., and turned off "Preserve Fav...Data" I follow every instruction I could find.

I'm stuck -- I cannot login to my Zen Cart Admin module -- I would appreciate any help anyone can offer. The shopping cart still seems to be working. A customer recently processed a sale, and we got paid (vis PayPal Website Pro). I just cannot login to the Admin section of our shopping cart, and I cannot seem to change, or reset my password. "Resend password" is not sending the password to me, but my website e-mail seems to be working.

http://www.activeart.net/
http://activeart.net/AGC/

Please let me know if I left out any pieces to the puzzle.

Thanks,
Jef

I meant to clarify that the the Admin login responds with:
"There was a security error when trying to login."

Thx,
Jef

**Update** I just tried to create a new customer login in my shopping cart. It is reporting an error -- my shopping cart does appear to be down. However, it appears that sales can be processed though the PayPal button (without loggin in). It looks like there's more than an Admin login issue.

Does anyone have a suggestion as to what might have happened, and what I should do?

Thx,
Jef