We just lost half our H.R. staff last month - JW, SG, and others left for bigger and better things, leaving us short a lot of HR people so they may just be bogged down...
That said, usually a lack of a response is better than a nasty-gram; it usually denotes that you passd the interview but they don't have a class date for you yet... Why they don't call back and say you passed and are awaiting a date is anyone's best guess, but... that's our corporate culture - mushroom philosophy.
If you want, call corporate at 901-348-4100 and ask for H.R., then just tell them you had a great time interviewing but haven't heard the status and are anxious to know when you can come to work... they'll probably tell you yea/nay but if it's nay they more than likely won't say why.
Good luck...