Promotions via mail codes does not seem to be working properly from the internal store. The example is mail code '7400' in conjuction with having 'RH300' in the shopping cart. This combination should product a $150 discount.
*** Bug 15937 has been marked as a duplicate of this bug. ***
This bug is now fixed. There were apparently some mod_perl gremlins at work that caused the bizarre failures seen yesterday.