MK5 Fiesta td strange fault

Hi, could anyone shed some light on my problem, i have a 2001 1.8td Fiesta van that has just hit 30,000 miles today, i had been on the road for 2 minutes this morning when all of a sudden my van lost 1/2 power (felt as if turbo had failed) and at the same time i noticed that the fan had come on, there were no warning lights or anything, i lifted bonnet to check it wasn't too hot and engine bay was fairly cold as it was first drive of the day, i stopped van for a few seconds and restarted and all was ok, i then travelled 30 miles with no probs, i thought at first the handbrake could have been sticking and causing it to run hot and feel as if it was lacking power but it seems free with no binding at all, any thoughts or ideas?, thanks, Steven