I have been contacted today by a relative who also has a VTD00 tumble dryer with exactly the same problem. Although I have not inspected the dryer yet, I suspect there is some wear in the timer drive mechanism, which will most likely need a replacement timer to overcome the problem. They are available from Hotpoint UK and cost around £36 plus delivery. It must be fitted by a competent person for safety reasons. I hope this helps.
Andy, January 2009