I'm running Arch Linux on an Acer laptop and my wirless connection doesn't stay up. After a while it disconnects, and when I try to reconnect I get stuck with a "Waiting for authorization" message. I have to retry several times before getting the connection stay up for few minutes. This happens with both networkmanager and wicd. The strange thing is that the iMac that sits next to the laptop connects fine, and when I use my laptop within the university wireless network it works normally.

How can I solve this problem?

EDIT: I've tried to connect manually following the steps

iwlist wlan0 scan
wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
dhcpcd wlan0

and it works, I can ping google. However, looking to wpa supplicant output I see that it keeps connecting and disconnecting. I'm using WPA2, and this seems to be a problem in authentication.

EDIT 2: as pointed out in the answers I forgot to mention my hardware/software specifications:

kernel:

Linux 3.0-ARCH

wireless card:

# lspci | grep -i net
07:00.0 Network controller: Intel Corporation WiFi Link 5100

module used

# lsmod | grep -i 80211
mac80211     216021  1  iwlagn

I use a Netgear DGN1000 modem/router

My dmseg output is shown here http://pastebin.com/8Tf7iage