We have 6 routerboard 133's in a building. all 6 run exactly the same configuration except for SSID's and IP's obviously.

One routerboard is behavioung very strangely. Half the time clients cannot SEE the router when they scan. When they can see the router they can sometimes connect, but most of the time they cannot because the router does not give out IP address to them. The routers are on default auth, default forward. Arp is enabled. A hotspot is configured on the router with dhcp which adds ARP leases. I know this should work since the other 5 AP's run exactly the same configuration and I have made sure they are identical.

Also the CPU of this 133 is always high. even if the wireless traffic is low. You can see the cpu/wireless statistics at http://larez.ath.cx/info/ if you go to Larez/bridge. Very Strange

I would really appreciate your opinion before attempting to remove access point.

How do you do your routing? Had something similar with RIP. For some reason the rip settings times were set to 0 on one specific board. Had the same weard kind if problems. Happend again with another board, bit knew of this. Mabe this help.

The router is one point of a star topology. so it only has one static route of 0.0.0.0/0 to go through its ether1 to the main server. that's it...
(no bridges or anything)

I have one guy on my network that connects to the hotspot with a laptop. It looks to me as if he has bridged this laptop with more devices behind it. because on my hotspot hosts list i can see my ip range 172.16.167.x with his laptops mac address, AND ALSO 192.168.1.x with the SAME MAC ADDRESS. Could this clients wireless bridge be causing me trouble?

Sounds like he has got a router with propably more than one computer behind it. Both computers will have the routers mac. Dont think this should bother your network though. How do your clients get ip? Also if you say scan, is this SSID or ip? Do clients sometimes diconnect also?

I have eliminated the bridging as problem. Clients get dhcp an address. scan is for ssid. which they dont see half the time. probably coz the router is MAXXED OUT CPU all the time. I struggle to winbox to it. Clients disconnect all the time. Anyway I'm officially over that router im just going to climb up and swop it for a dif one.