I’m just doing a new install into root directory now and using WP 4.1 doesn’t seem compatible with WP E commerce 3.9.1. The brand new installation keeps blank screening suggesting that some paths aren’t correct in the new version of WP 4.1 and the plugin is trying to find those paths to no avail. I’d have to have a look further into the new release of 3.9.1 but I’d suggest rolling back you database and re installing the old plugin.
