Sony NV-U70T GPS Receiver

My wife (for whom the GPS was purchased to use in her automible travels) and I were very pleased with this product with the preloaded USA map which takes up all of the GPS's 1GB of memory. To use area maps - East Coast Map A - in this case, the USA map is first deleted to make room for the other maps with richer detail, particularily Points of Interest (POI).

There is a problem with loading maps in the NV-U70 that Sony technical support has not yet been able to resolve. Since I have a 7 day window to return the GPS as defective, it shall be returned forewith as it is now unusable.

Here is a description of the problem I encountered:

"Cannot load new maps into new NV-U70 GPS. Consistently receive ambiguous error messages at end of map load attempts such as "An error occurred" or in one instance "The parameter is incorrect".
Have followed Map Manager and Sony FAQ's with deleting USA Map, attempt to install East Coast A Map multiple times (runs about one hour, then error) and then attempt to reinstall USA Map (runs about two hours, then error) when I receive these error messages. GPS now has no map loaded because of these errors."