Thank you for your feedback.
The UPnP trick did not for me, however a fresh installation of Windows 8 helped.
The point is that my Windows 8 was on New Series 9 Samsung and maybe the drivers and preinstalled software have had conflicts with Skype. Now, when the Windows 8 is a fresh install, there is no issue with Skype.
I tried to rename but it said it is opened in another file in skype and was not allowed to rename the folder at all ;(
This option isn't even available. Thanks anyway.
The option to disable uPnP is only available from Skype main window. It’s not available from the login window.
Have you tried to rename the Skype settings folder?
Same problem here, I can't rename this folder.
However I really don't want to loose all my chat history stored in this folder either.
It will be very easy to re-establish your Skype history after renaming the %appdata%\Skype folder. The history is saved in the main.db file in the folder named as your Skype name, and moving this file back to the new %appdata%\Skype folder will re-establish the history.
In order to be able to rename the folder you must ensure that Skype is not running on your computer.
Quit Skype or use Windows Task Manager to kill any Skype.exe process. Go to Windows Start and in the Run box type %appdata% and then press Enter or click the OK button. The Windows File Explorer will pop up. There locate a folder named “Skype”. Rename this folder to something different, e.g. Skype_old. Restart Skype.
N.B. If needed, you will still be able to re-establish your call and chat history. All data is still saved in the Skype_old folder.
Unfortunately in Windows 8 Skype cannot be killed in Task Manager. When attempting to do this under the Processes tab it simply doesn't respond, in the Details tab is say "access denied" as pargev noted.
I was able to do this by changing Skype to not auto start on computer startup. Then I restarted and was able to sign in and disable uPnP.
I really hope this continues to work. I was startled to find how serious a problem this Windows 8 and Skype issue caused to my work and how hard it was to solve.