Thank you for the reply Graham, I think you are right, it is the synch feature that is causing the problem.
Unfortunately it doesn't solve the issue since the laptop is often used for presentations and many students come with their own memory sticks (yes I know that it increases the risk of viruses but it is the only practical possibility), and so it is often a new memory stick which has never been in the computer before.
Oh well, I suppose that I will just have to keep the taskmanager open to kill the process when it starts. I would prefer Vista to show a little less autonomy
all the best / Björn