I've been tried: removed skype, removed completely skype by deleting the registry keys as well, editing the main.db file with the data base editor mentioned above and still nothing.
Try to reset all Skype settings.
First, skype sign out or use Windows Task Manager to kill any Skype.exe process. Go to Windows Start and in the Search/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.
Next step: Click Windows Start and in the Search/Run box type %temp%\skype and then press Enter or click the OK button. Delete the DbTemp folder.
If needed, you will still be able to re-establish your call and chat history. Data is still saved in the Skype_old folder.