Runliveupdate problem or a glitch?

Hey there N.C

 

  I've ran RunLiveupdate as I usally do and always it shows good green check marks. This time one of last time updates showed an error . I have tryed again and it was good. My concern why did it fail the last update? I dont want to happen again.

 

Windows Vista Home preimun 64 editon HP Pavillion dv7 Notebook . Norton 2011