USPS and UPS Modules intermiittently disappear...HELP!!

Have been using USPS and UPS modules on my second Zen Cart and, after 4 months, the modules disappear and an error shows up in the cart saying that either or both don't ship to a particular address.

I tried removing and reinstalling them. They both work, then one doesn't, then both don't. I removed UPS, thinking maybe there's some kind of conflict between the two. Placed a test order with USPS and it worked. Tried to place another test order and it was gone again.

HELP!!!

This can happen on some addresses such as USPS and UPS conflicts as to what Country an address is from ...

USPS wants all US Territories, Islands, etc. to be "states" of the Country United States ...

UPS wants all of the US Territories, Islands etc. to be their own Countries ...

Have you a Ship From and Ship To that you are having trouble with?

NOTE: there are also rules for minimum/maximum weights, order amount and shipping methods that can affect things ...

Thank you for replying to my post.

This weirdness started happening suddenly on a site that's been up for over 4 months, with both shipping modules active. A customer in Georgia was trying to purchase and have something shipped to her from Texas.

I thought it could be something to do with the SSL, because accessing the server while in SSL was a bit slow (actually hung up on Logoff). The webhost SSL tech "specialist" said it wasn't a server side issue, although he had sent an autoresponse email within 30 seconds of openng my detailed support ticket (I observed this, since I was waiting desparately for an answer). He suggested I "hire" one of their webdev people to look at my code, but I haven't made any changes to the site since it's been up.

The store owner asked what other choices there were, and we decided to switch to per weight unit shipping.

Thanks again, for your reply.