My WNDR3800 Issues

I've been researching this pretty extensively over the past few days, but nothing so far has worked.

background:  since I can think of, I've been on the wrt-54g linksys routers, and then on the buffalo dd-wrt router.  Recently I switched to the Netgear WNDR3800.

Issues:

At first I was fine out of the box, everything set up all nice and working.  Then about a week later I noticed that my 2.4ghz channel had dropped completely.  This wasn't the biggest deal, as only my phone used that signal, and everything else I had used the 5g channel.  however, being who I am, I couldn't let it go so i tried to fix it.  I was currently on the 1.0.0.40 firmware, tried downgrading, 30-30-30 resets, nothing worked.  

So i load up the DD-WRT brainslayer that I read about.  I'm on r18777 right now.  Nothing is fixed!  The problem's i'm still getting are:

1) No 2.4ghz channel.  Even though the router says it's running, my laptop/phone can't see it.  Even running in Mixed as opposed to NG, i get nothing.  

2) No 40mhz (Turbo) Channel width.  I only get Full (20mhz).  This is odd, right?  As such, I find my wireless surfing really slow.  I have my encryption set to WPA2 Personal AES, which is what it should be, right?

any advice would be helpful.  if you need more info, let me know and i shall provide!