Every day or two, my Skype stops working. Upon signing out, skype informs me that "Can't open skype. You are already signed in on this computer. Please sign out and try again." what do I do? I can't sign out because I already did. I tried exiting the program, but that gave me the same message, and I even re-installed, and I keep getting the same error.
Quit Skype or use Windows Task Manager to kill any Skype.exe process. Go to Windows Start and in the Search/Run box type %appdata%, press Enter or OK button. The Windows File Explorer will popup. Locate there a folder with the name 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 history. All data are still saved in the Skype_old folder.