Hi tere
Why don't you rather open a private ticket here, and let us have a look? I am sure it is only your site having issues as we have had no other problem yet. You can as well try to deactivate all plugins apart of WooCommerce and ATUM. See if that works. If it does, start activating plugin by plugin. You will find the one that causes the issue.
You will have to upgrade to 1.5 by some point because it is fully compatible with the new WooCommerce system.
If not, just delete ATUM completely and download the previous version from the dropdown at the bottom of that page.
Hope this helps.
Pavel