Same here :
kernel 2.6.32-5-686
wpasupplicant                                 0.6.10-2.1 
eth1: Broadcom BCM4315 802.11 Hybrid Wireless Controller 5.60.48.36 

Feb 15 14:09:42 longitude wpa_supplicant[1576]: CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys
Feb 15 14:09:42 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  completed -> disconnected
Feb 15 14:09:42 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  disconnected -> scanning
Feb 15 14:09:45 longitude dhclient: Internet Systems Consortium DHCP Client 4.1.1-P1
Feb 15 14:09:45 longitude dhclient: Copyright 2004-2010 Internet Systems Consortium.
Feb 15 14:09:45 longitude dhclient: All rights reserved.
Feb 15 14:09:45 longitude dhclient: For info, please visit https://www.isc.org/software/dhcp/
Feb 15 14:09:45 longitude dhclient: 
Feb 15 14:09:45 longitude dhclient: Listening on LPF/eth1/00:23:4e:ab:8d:00
Feb 15 14:09:45 longitude dhclient: Sending on   LPF/eth1/00:23:4e:ab:8d:00
Feb 15 14:09:45 longitude dhclient: Sending on   Socket/fallback
Feb 15 14:09:45 longitude dhclient: DHCPRELEASE on eth1 to 172.19.8.1 port 67
Feb 15 14:09:45 longitude avahi-daemon[1487]: Withdrawing address record for 192.168.1.75 on eth1.
Feb 15 14:09:45 longitude avahi-daemon[1487]: Leaving mDNS multicast group on interface eth1.IPv4 with address 192.168.1.75.
Feb 15 14:09:45 longitude avahi-daemon[1487]: Interface eth1.IPv4 no longer relevant for mDNS.
Feb 15 14:09:45 longitude dhclient: receive_packet failed on eth1: Network is down
Feb 15 14:09:45 longitude wpa_supplicant[1576]: CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys
Feb 15 14:09:45 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  scanning -> disconnected
Feb 15 14:09:45 longitude dhclient: Internet Systems Consortium DHCP Client 4.1.1-P1
Feb 15 14:09:45 longitude dhclient: Copyright 2004-2010 Internet Systems Consortium.
Feb 15 14:09:45 longitude dhclient: All rights reserved.
Feb 15 14:09:45 longitude dhclient: For info, please visit https://www.isc.org/software/dhcp/
Feb 15 14:09:45 longitude dhclient: 
Feb 15 14:09:45 longitude dhclient: Listening on LPF/eth0/00:21:9b:e0:44:5a
Feb 15 14:09:45 longitude dhclient: Sending on   LPF/eth0/00:21:9b:e0:44:5a
Feb 15 14:09:45 longitude dhclient: Sending on   Socket/fallback
Feb 15 14:09:45 longitude dhclient: DHCPRELEASE on eth0 to 193.40.5.35 port 67
Feb 15 14:09:45 longitude dhclient: send_packet: Network is unreachable
Feb 15 14:09:45 longitude dhclient: send_packet: please consult README file regarding broadcast address.
Feb 15 14:09:45 longitude kernel: [13853.020452] tg3 0000:09:00.0: irq 29 for MSI/MSI-X
Feb 15 14:09:46 longitude NetworkManager[1541]: <info> (eth1): roamed from BSSID 00:0E:8E:7A:32:08 (ap11g) to (none) ((none))
Feb 15 14:09:48 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  disconnected -> scanning
Feb 15 14:09:53 longitude wpa_supplicant[1576]: Trying to associate with 00:0e:8e:7a:32:08 (SSID='ap11g' freq=2437 MHz)
Feb 15 14:09:53 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  scanning -> associating
Feb 15 14:09:53 longitude wpa_supplicant[1576]: Association request to the driver failed
Feb 15 14:09:54 longitude wpa_supplicant[1576]: Associated with 00:0e:8e:7a:32:08
Feb 15 14:09:54 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  associating -> associated
Feb 15 14:09:54 longitude wpa_supplicant[1576]: CTRL-EVENT-CONNECTED - Connection to 00:0e:8e:7a:32:08 completed (reauth) [id=0 id_str=]
Feb 15 14:09:54 longitude NetworkManager[1541]: <info> (eth1): supplicant connection state:  associated -> completed
Feb 15 14:09:58 longitude NetworkManager[1541]: <info> (eth1): roamed from BSSID (none) ((none)) to 00:0E:8E:7A:32:08 (ap11g)

Stopped network-manager, using wicd, it still disconnects from time to time, but is able to reconnect on itself

Looks like wpa-supplicant decides to drop connection, but network-manager can't properly associate back to the AP.  

Can't connect to wpa_supplicant using wpa_cli:
Failed to connect to wpa_supplicant - wpa_ctrl_open: No such file or directory, so can't get debug information.