Hi everyone. Sorry to ask, but Ive not been able to find my problem with searches, so, its time to make a post! Thanks in advance for your help!

OK...
Ive got a 1.37 store setup and running...
url is : http://www.flamemasks.com/zshop

I believe this is an accurate list the few mods installed...
ImageHandler 2
EZ Populate
Flat Clone (3x)
Stock by Attributes
Master Password

Ive setup my shipping options like this:
Can. & Mex. Standard.................flat (stock Zen)
USA First Class...........................flatClone
USA Priority................................flatClone_two
Can. & Mex. INTL. Priority............flatClone_three

Zone Rate setup for rest of the world.

I also have freeshipper engaged for downloadable files and Free Shipping specified for US Customers orders over $50. All the zone stuff seems to work fine, and shows to the appropriate geological groups during demo tests.

My problem is that when a US Customer (under $50) selects Priority Shipping, when they proceed with checkout, the option is changed to 1st Class shipping during step two, and even if the customer realizes the change, when they go back to step 1, select priority again..it still reverts to 1st class in step 2 of checkout.

Ive looked at the flatClone & flatClone_two php files, but dont see anything obvious that would cause this issue, not that I couldnt have missed it of course, but if anyone happens to know of a similar issue, and maybe direct me to the right area/file to inspect...I would appreciate the help!
Also I did install two other mods after the last flatClone, but I didnt notice any files which would have been affected.
Thanks!