LiveUpdate 10 minutes cycle not working.

Hi, have always found it comforting that the LiveUpdate cycle on my machines was always 10 minutes, felt safe. Well today that 10 minute cycle on  my machines is all over the place, at this very moment  the cycle is showing 23 minutes on one machine, and  29 minutes on my second machine. Did a new installation on one machine until I realized that the second machine was also failing to show it was updated, it naturally made no difference. Been using Norton security suite for three years and this is a first. Just done another check and neither machine has updated yet. Running LIveUpdate does update the machines, but it's that 10 minute cycle telling me all is well that I'm missing. Any thoughts ?

Mike