Description of problem:
----------------
Can't connect to wlan0. I get the message:
"Cannot activate network device wlan0!
Device wlan0 does not seem to be present, delaying initialization. "

Version-Release number of selected component (if applicable): 3945ABG
----------------
0b:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG Network Connection (rev 02)

How reproducible:
----------------
When activating wlan0, the error message is displayed and the wi-fi doesn't connect.

Steps to Reproduce:
----------------
1. system-config-network
2. select wlan and activate
3. error message
  
Actual results:
----------------
Wlan doesn't work.

Expected results:
----------------
Wlan0 should work out of the box.

Additional info:
----------------
Messages tracked on dmesg:
iwl3945 0000:0b:00.0: enabling device (0000 -> 0002)
iwl3945 0000:0b:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
iwl3945 0000:0b:00.0: setting latency timer to 64
iwl3945: Detected Intel Wireless WiFi Link 3945ABG
i801_smbus 0000:00:1f.3: PCI INT B -> GSI 17 (level, low) -> IRQ 17
iwl3945: Error: saturation power is -1, less than minimum expected 40
iwl3945: Invalid power index
iwl3945: initializing regulatory failed: -5
iwl3945 0000:0b:00.0: PCI INT A disabled
iwl3945: probe of 0000:0b:00.0 failed with error -5

Thread on FedoraForum: 
http://forums.fedoraforum.org/showthread.php?p=1146142#post1146142