aspire timeline wlan rfkill switch blocked

Hello,

I’m running 11.2(KDE 4.3.5) on an Aspire Timeline 4810T. From time to time it happens, that without apparent reason the wifi stops working. Following a tipp on some forum I installed rfkill.
Now, if I do

rfkill unblock all

it works again immediately. It is not a pressing problem as it can be dealt with immediately, but I’m curious. What might be the reason that the rfkill switch gets blocked seemingly randomly?

Some additional info:

# hwinfo --wlan
21: PCI 200.0: 0282 WLAN controller
  [Created at pci.318]
  UDI: /org/freedesktop/Hal/devices/pci_8086_4232
  Unique ID: y9sn.4sCLS2kIqkC
  Parent ID: qTvu.8Makl3iDVc3
  SysFS ID: /devices/pci0000:00/0000:00:1c.1/0000:02:00.0
  SysFS BusID: 0000:02:00.0
  Hardware Class: network
  Model: "Intel Wireless WiFi Link 5100"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x4232 "Wireless WiFi Link 5100"
  SubVendor: pci 0x8086 "Intel Corporation"
  SubDevice: pci 0x1301
  Driver: "iwlagn"
  Driver Modules: "iwlagn"
  Device File: wlan0
  Features: WLAN
  Memory Range: 0xd2400000-0xd2401fff (rw,non-prefetchable)
  IRQ: 27 (no events)
  HW Address: 00:22:fb:44:aa:d8
  Link detected: yes
  WLAN channels: 1 2 3 4 5 6 7 8 9 10 11 12 13 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140
  WLAN frequencies: 2.412 2.417 2.422 2.427 2.432 2.437 2.442 2.447 2.452 2.457 2.462 2.467 2.472 5.18 5.2 5.22 5.24 5.26 5.28 5.3 5.32 5.5 5.52 5.54 5.56 5.58 5.6 5.62 5.64 5.66 5.68 5.7
  WLAN encryption modes: WEP40 WEP104 TKIP CCMP
  WLAN authentication modes: open sharedkey wpa-psk wpa-eap
  Module Alias: "pci:v00008086d00004232sv00008086sd00001301bc02sc80i00"
  Driver Info #0:
    Driver Status: iwlagn is active
    Driver Activation Cmd: "modprobe iwlagn"
  Config Status: cfg=no, avail=yes, need=no, active=unknown
  Attached to: #9 (PCI bridge)

Thanks!