The problem is now solved, thanks. For other people having this PHP error: In my case, the "form generator" (CCSFG utility) had the old password stored in it. Thankfully, I didn't actually have to redesign my embedded form, I just went through the simple installation steps 3 through 8 (from this PDF Documentation.pdf that's with the Constant Contact Signup Form Generator utility.) It will ask for your old password first so you can enter your new one. For those of you who don't want to bother tweaking a new form: I didn't have to actually use the new form code I generated; the old form now works because it updated the password.
... View more