Important until further notice you must Replace AdminImport !
The latest version of PrestaShop v1.4.2 has made changes to the AdminImport script that is used for importing images with a csv file. Currently the latest will take the image csv file they require and put all products in random categores, and not leave them where they belong.
Until further notice be sure that any PrestaShop version below v1.4.2 replaces the AdminImport.php file with the one supplied below.
To replace just upload the zipped file below over /Admin_directory/tabs/AdminImport.php, if you forgot to do this or didn't read this FAQ and have already used the AdminImport that is in the PrestaShop download / installation. Then you'll have to replace that file and start all over in STCtoPresta.
ADDENDUM:
PrestaShop v1.4.3 has a new image system where the images are separated in the /img/p directory and it appears that the AdminImport.php file has been fixed to accommodate this new change. It also appears to be working fine with the few tests that I've done.
I do not know if upgrading from previous versions of PrestaShop will affect how the images are currently uploaded. If you plan to upgrade I would advise deleting all the previous images so that you can import into their new directory listing they’ve change over to.