Wireless constantly dropping

I've been battling wireless issues at my new job for more than a month.  I feel like I've tried about everything.  

We had three or four access points in our two story building.  They were all part of the LAN (I know...).  Signal strength and quality looks good.  I've tested with programs like inSSIDer.  However the connection seems to drop every few minutes, on each access point.  I've moved them to different locations, changed the channels, gotten closer to the access points.  Ran wireshark.  I even bought nice new Linksys routers and created a temporary wireless network on DMZ to get it completely off the LAN and away from other traffic.  Same thing.

Right now it's 7:30 am.  Nobody is here.  I'm sitting ten feet away from the new wireless router.  It's on the DMZ.  Nobody is on it but me.  Nobody is on the DMZ at all.  All other routers and access points are spaced out on different channels.  Strength and Quality are incredible.....    I'm getting 10Mbps up and down on speed tests...   Yet the connection keeps dropping.

This would point to hardware or cable problems...  but the same thing was happening when wireless is on LAN.  Completely different cables, switches.  Only thing similar is the firewall and WAN cable and router.  We don't experience any problems on our wired connection.

So i'm pretty perplexed.  Any advice would be greatly appreciated.  Thanks!