WiFi Authentication issues/failed after Standby/Hibernate after Upgrading to Windows 8.1 with Intel 4965AGN on Dell XPS M1330 with Fritz!Box 7330

Before upgrading from Windows 8 to 8.1, everything was working fine on my computer. After upgrading to 8.1 yesterday, it happens, that my Computer does not re-connect to my WiFi after StandBy/Hibernate. I have to disable/enable the Adapter to connect to the WiFi again.
My Router reports that the "Autentication failed" for my adapter's MAC-Address. I have a Fritz!Box 7330 with latest Firmware. The error message is "WLAN-Anmeldung ist gescheitert: Autorisierung fehlgeschlagen".
The Network Adapter is a Intel® Wireless WiFi Link 4965AGN in a Dell XPS M1330.
I went through numerous threads on the forums reporting similar issues with Intel WiFi Adapters, but none of the suggestions fixed my Problem.

The Driver Version displayed for the Adapter is 13.3.0.137, dated 15.08.2010 by Microsoft.

How-I-fixed it:
In the device Power Management settings uncheck "Allow the computer to turn off this device to save power". Since i did this, the WiFi is stable.

Update:
Found out that the same problem occurs with Intel 3945 ABG network adapter. Fix also works for this adapter.

Similar threads about WiFi-Issues with Windows 8.1:
http://answers.microsoft.com/en-us/profile/9845b657-0ff4-4ccb-95b9-a0ea3912f017

http://answers.microsoft.com/en-us/windows/forum/windows8_1_pr-hardware/wifi-not-working-in-windows-81/c3d91dea-c3ea-4f62-9430-5b0b6c6a664b

http://ishamsaid.tumblr.com/post/54179009758/atheros-wifi-problem-in-windows-8-1

http://answers.microsoft.com/en-us/windows/forum/windows8_1_pr-hardware/wifi-not-working-in-windows-81-in-acer-aspire-5920/13db3375-c2db-4194-b9ed-a6d29215dba2

http://answers.microsoft.com/en-us/windows/forum/windows8_1_pr-hardware/i-upgraded-to-windows-81-preview-and-now-my-wifi/36497036-1829-4b29-bcce-e076c57ef933

http://answers.microsoft.com/en-us/windows/forum/windows8_1_pr-hardware/feedback-windows-81-after-i-upgraded-wifi-problem/683a87b5-c154-442d-a6a8-eef4db558edb

http://social.technet.microsoft.com/Forums/windows/en-US/0331a9fe-3632-4e8c-a611-5ab2954bf67d/windows-81-pro-wifi-issues?forum=w8itpronetworking

http://answers.microsoft.com/en-us/windows/forum/windows8_1-hardware/windows-81-wlan-not-working-after-sleep/51921f8e-8d25-458f-8a57-f2ae90f3a71d