USPS Web Tools Errors

Over the past week or so, my shopping cart has not displayed shipping cost quotes for USPS. I was made aware of the problem by one of my customers who complained about errors and not being able to use any other shipping service other than UPS, which costs more than USPS. The error message is “An error occurred in obtaining USPS shipping quotes. If you prefer to use USPS as your shipping method, please try refreshing this page, or contact the store owner.” I was using an older version of the USPS shipping module at the time, and subsequently upgraded the module to the most current one identified as USPS Version Date 2015-05-31. Several tests and customers later have resulted in the same failure and error message. Shipping methods I have selected are limited to Priority Mail, Priority Mail Express, and Priority Mail International. My Zen-cart version is 1.3.8a. PHP version 5.2.17 .
I have changed various settings in admin several times to hopefully stumble upon a solution to no avail. Currently my module setting are:
USPS Version Date
2015-05-31

Enable USPS Shipping
True

Full Name or Short Name
Long

Enter the USPS Web Tools User ID
xyz…

Which server to use
production

Quote Sort Order
Price-LowToHigh

Handling Fee - US
0

Handling Fee - International
0

Handling Per Order or Per Box
Box

Decimal Settings
2

Tax Class
Non-Taxable Services

Tax Basis
Shipping

Shipping Zone
--none--

Sort Order
2

All Packages are Machinable?
True

USPS Options
Display weight

USPS Domestic Transit Time Calculation Mode
NEW

USPS Domestic minimum Length
8.625

USPS minimum Width
5.375

USPS minimum Height
1.625

USPS International minimum Length
9.50

USPS minimum Width
1.0

USPS minimum Height
5.50

Enable USPS First-Class filter for US shipping
False

Shipping Methods (Domestic and International)
0, .21875, 0.00, 0, .8125, 0.00, 0, .8125, 0.00, 0, .8125, 0.00, 0, 70, 0.00, 0, 70, 0.00, Priority MailTM, 0.1, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 15, 0.00, 0, 20, 0.00, 0, 25, 0.00, Priority Mail ExpressTM, 0.1, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, 70, 0.00, 0, .21875, 0.00, 0, 4, 0.00, 0, 4, 0.00, Priority Mail InternationalRM, 0.1, 66, 0.00, 0, 4, 0.00, 0, 4, 0.00, 0, 20, 0.00, 0, 20, 0.00, 0, 66, 0.00, 0, 4, 0.00, 0, 20, 0.00, 0, 70, 0.00, 0, 70, 0.00

Extra Services (Domestic)
Certified MailRM, N, USPS TrackingTM Electronic, N, USPS TrackingTM, N, Insurance, N, Priority Mail Express Insurance, N, Priority Mail Insurance, N, Adult Signature Restricted Delivery, N, Adult Signature Required, Y, Registered MailTM, N, Collect on Delivery, N, Return Receipt for Merchandise, N, Return Receipt, N, Certificate of Mailing (Form 3665), N, Certificate of Mailing (Form 3817), N, Signature ConfirmationTM Electronic, N, Signature ConfirmationTM, N, Priority Mail Express 1030 AM Delivery, N, Certified MailRM Restricted Delivery, N, Certified MailRM Adult Signature Required, N, Certified MailRM Adult Signature Restricted Delivery, N, Signature ConfirmationTM Restricted Delivery, N, Signature ConfirmationTM Electronic Restricted Delivery, N, Collect on Delivery Restricted Delivery, N, Registered MailTM Restricted Delivery, N, Insurance Restricted Delivery, N, Insurance Restricted Delivery (Priority Mail Express), N, Insurance Restricted Delivery (Priority Mail), N

Extra Services (International)
Registered Mail, N, Insurance, N, Return Receipt, N, Electronic USPS Delivery Confirmation International, N, Certificate of Mailing, N

Retail pricing or Online pricing?
Online

Debug Mode
Off
My suspicion is that my shared server host has made some changes that may have been a factor. In the past they have confirmed that curl is enabled. However, since the USPS API is undergoing so may changes recently, I am in a cloud of various scenarios. Any solutions or suggestions would be appreciated.