This just happened to me today as well. I installed the login redirect plugin this morning and it was working fine for regular users. I tried to access the admin tonight and it just does nothing, no errors, no admin console, nothing. As soon as I disabled the redirect plugin, I was able to get into the admin console again.
I downloaded the beta via the link in the post above (shown below)
https://github.com/wp-e-commerce/WP-e-Commerce/archive/3.9.2.zip
but when I install it, it shows as still 3.9.1. Our issue is the opposite, an item that is marked as exempt from taxes is calculating tax in the shopping cart. This issue occurs with both the original 3.9.1 and the beta version. Please let me know if there is an alternate download for a version that will fix the tax issue. We are expecting a lot of activity on the broken item in the next few days so the quicker we can fix it the better.
