Bob,
Sounds like you need to ask your host to upgrade your ShopSite to the v9.0.3 maintenance release, see:
http://support.shopsite.com/kbase/view_answer.php?questionID=S5527
* fixes an issue with USPS First-Class Mail rates being much too high in the shopping cart since changes USPS made to their API responses approximately in early March, 2008.
Besides this, there are several other USPS fixes/enhancements:
* fixes an issue with USPS shipping that would occur with US shoppers who enter their entire Zip+4 in the shopping cart postal code field and would get no USPS rates and an error message stating 'There are no USPS shipping options that can ship the entire order.'
* fixes a USPS issue with APO and FPO addresses that would cause an Internal Server Error in the shopping cart if a shopper entered an APO or FPO zip code in the shopping cart when the USPS feature was enabled.
* adds Media Mail and Library Mail shipping options to the USPS shipping integration.
* adds clarification to the USPS shipping registration instructions to notify USPS that the USPS APIs used by the ShopSite shopping cart are, specifically, the 'Rate Calculators APIs'.
* adds a warning for merchants entering product shipping dimensions if they enter a height or width that is greater than the length. Generally, the longest dimension should be the Length, which should be in the first position in the dimension entered. Also, an email will be sent to the merchant if a shopper attempts to order a product with dimension settings larger than those allowed by USPS.
-Loren