Shawn, we are (all of a sudden, starting yesterday) getting an error when trying to process credit cards from multiple PC's using authorize.net. The error that we get almost immediately after clicking the "Bill" button says, "ERR: missing or invalid activation key. Contact the vendor of this software for a new activation key." Credit cards can be processed from only one of the tech computers. We need to figure out what's causing this error as quickly as possible. Customers can't do online charges either. We have contacted Authorize.net already and they don't have any activation keys, just the transaction key which is correct (as I stated earlier, one machine is processing OK). And the Authorize.net Virtual Terminal is still working. As a side note, I upgraded to 3.3.8 from 3.3.6 on Nov. 1st, and it was working until Nov. 3rd, so I don't expect it was because of the upgrade, but I wanted to make sure there's not anything I'm overlooking from the upgrade.