I checked out the website and logged in using the provided credentials. Unfortunately the redirect didn't work, I'm pretty much stuck on the home page :/. However from reading your description I understand what needs to be done and am confident I can fix it :). I have eight years experience actively working in php, so bug fixes are nothing I haven't handled 100000x before. Anyways, we can discuss over aim/skype if you want or you could just hit me up with your site details and I'll get right on it!
I can probably have the site fully fixed by the end of the day :).
Edit: Reviewed your additions, its most likely a cookie issue and shouldn't take much time to fix. If it is a simple 15-minute fix I'll knock the price down :)