Dear Sir,I have a Toshiba notebook, with Windows Vista Home Premium and I'm trying to download some security updates but always I receive an error message and the updates are not downloaded.Code 800B0100 - Windows Update encountered an unknown error !!!!Could you have an idea to solve this problem ?Thanks in Advance,Marcelo

See:"Error message when you try to use the Windows Update or Microsoft Update Web sites to install updates: "0x800B0100""http://support.microsoft.com/kb/956702 If still no joy...Please, start a free Windows Update support incident request: https://support.microsoft.com/oas/default.aspx?gprid=6527 Support for Windows Update: http://support.microsoft.com/gp/wusupport For home users, no-charge support is available by calling 1-866-PCSAFETY in the United States and in Canada or by contacting your local Microsoft subsidiary. There is no-charge for support calls that are associated with security updates. For better assistance please ask for help in the Microsoft Windows Update specific newsgroup. In your newsreader:news://msnews.microsoft.com/microsoft.public.windowsupdate Via Web: http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.windowsupdate [If this post helps to resolve your issue, click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.]Vincenzo Di Russo - Microsoft MVP Windows Internet Explorer, Windows Desktop Experience & Security - Since 2003

Dear Vincenzo,Thanks for your help !I'll try your directions and back to you with the results.Marcelo.Fior