site works fine on my host & sandbox but dies in a diff host

How did you transfer the files to the new site? There are often many URL’s and paths stored in the WP database in ‘serialized’ form. That is, the strings are stored along with their length. Using a normal ‘search and replace’ will cause problems if the new URL or path is a different length from the old one. You must use a special tool to copy from one site to another.

Here is an article with the steps that I use to migrate (copy) a site: http://wordpress.mcdspot.com/2012/08/22/migrating-a-wordpress-site-step-by-step/