When you add a new product, the ecommerce system tries to make a subdirectory to store stuff like uploaded images and ?? (don't remember). I would bet that you don't have one of the parent directories of web/greetingchecks/data/ecommerce/product/49 - 49 is the product_id I would bet. Check your file system for existance of the web/greetingchecks/data/ecommerce/product directory - and check that the web server user can write to it. If I recall, you can relocate the set of directories using one of the parameters in the ecommerce section of the .ini config file (I am guessing here that you are using an ecommerce module from an ACS or OpenACS 3.x series).
