The error code 401 is due to a conflict in Vista's virtualization system. Here's how to fix this: Click on the Windows logo at the bottom left (Start), write APPDATA in the text box and click Enter. On the window that will open go to the Local > Virtualstore > Program Files. Delete the folder called either Panda Software or Panda Security. Open the antivirus. Enter your update details again and update your security solution.