Customers cannot log in after update

[DarkMonohue]

Summary: Following an update today from 1.3.9c to 1.5.3, it seems that customers cannot log in.

Detail: Clicking the main "Log In" link near the top of the page or clicking "Go to Checkout" icon from the shopping cart both open a page with a box for returning customers to log in. When I enter my dummy/test account info and click the "login" button, I am returned to the shopping cart. At that point I am not logged in. There is no error message.

Background: I updated the store today, following the standard zc_install procedure. Modules transferred over include a template, UPS and USPS shipping modules, and PayPal Express checkout. Most of the work is complete and I believe I am about ready to reopen the store (currently in maintenance mode). AFAIK, the store was working fine prior to the update.

Assuming I am reading these correctly, PHP version is 5.2.17 and MySQL version is 5.0.77

Site in question is at www.s v 3 p o w e r.com/store in case anyone wants to take a look.

I would be more than happy to post anything else that would be helpful.

If anyone sees any other glaring issues, or has tips on improvements that should be made, I'd love to hear them.

Disclaimer/Apology: This store is for a small volume hobby business and I don't make enough money on it to warrant a lot of time in administration. It is a basic, dated format, but it serves its purpose well enough for now. Translation: I am not nearly as savvy as most of you. Please dumb down your suggestions accordingly...this isn't what I'm good at!

[DarkMonohue]

Well, this is interesting.

I bounced around verifying my PayPal checkout settings, tried (unsuccessfully) to get their sandbox to work, got a security error 10002 (possibly a result of sandbox or debug mode?). Then I switched it all back to normal and rebooted the computer.

It all seems to be working now.

Feel free to take a look just the same in case anything else needs a tune-up...