Can't connect to my wi-fi N network on vivid: authentication timed out

I can't connect to my wi-fi with my laptop.

I get this error message in the syslog.
Apr 8 22:25:35 ubuntu kernel: [ 793.895555] wlan0: authentication with 10:bf:48:e5:d1:b8 timed out

ubuntu@ubuntu:~$ lshw -c network
WARNING: you should run this program as super-user.
  *-network
       description: Ethernet interface
       product: Ethernet Connection I217-V
       vendor: Intel Corporation
       physical id: 19
       bus info: pci@0000:00:19.0
       logical name: eth0
       version: 05
       serial: 00:90:f5:f8:ef:86
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=2.3.2-k duplex=full firmware=0.12-3 ip=192.168.2.208 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
       resources: irq:29 memory:f7e00000-f7e1ffff memory:f7e3d000-f7e3dfff ioport:f080(size=32)
  *-network
       description: Wireless interface
       product: Wireless 3160
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: wlan0
       version: 83
       serial: a0:88:69:39:ae:d6
       width: 64 bits
       clock: 33MHz
       capabilities: bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=3.19.0-10-generic firmware=25.15.12.0 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn
       resources: irq:32 memory:f7c00000-f7c01fff

Attached is the full syslog.
This machine has been working more or less ok on vivid for at least three months. Sometimes it refused to connect to the wi-fi, but after a restart it started working.
Recently I changed the network from G to N, and recently did an upgrade to the latest vivid. I had some problems booting, so I also recently fully removed upstart. It boots fine with systemd, and everything else seem to be working.
I've just tested with a daily vivid live USB, and the same problem happened.

I'm connecting to the same network using the same password with my other machine.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: network-manager 0.9.10.0-4ubuntu11
ProcVersionSignature: Ubuntu 3.19.0-10.10-generic 3.19.2
Uname: Linux 3.19.0-10-generic x86_64
ApportVersion: 2.16.2-0ubuntu4
Architecture: amd64
CasperVersion: 1.356
CurrentDesktop: Unity
Date: Wed Apr 8 22:20:03 2015
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IpRoute:
 default via 192.168.2.1 dev eth0 proto static metric 1024
 169.254.0.0/16 dev eth0 scope link metric 1000
 192.168.2.0/24 dev eth0 proto kernel scope link src 192.168.2.208
LiveMediaBuild: Ubuntu 15.04 "Vivid Vervet" - Beta amd64 (20150326)
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 eth0 ethernet connected /org/freedesktop/NetworkManager/Devices/1 Wired connection 1 cf5cb021-0df1-4f13-b74c-c3e9c6749a30 /org/freedesktop/NetworkManager/ActiveConnection/2
 wlan0 wifi disconnected /org/freedesktop/NetworkManager/Devices/2 -- -- --
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/0 -- -- --
nmcli-nm: Error: command ['nmcli', '-f', 'all', 'nm'] failed with exit code 2: Error: Object 'nm' is unknown, try 'nmcli help'.