"Handbrake On" warning light
 

Hello, can someone help me please? I have owned my 51 plate 1.9TDI (130), 6 spd, estate, for 5 years. The car has done 120,000 miles. It is a great car. However it has now developed a fault. Whilst driving to work the other morning the "Handbrake On" notice displayed on the dash together with a red circle with an exclamation mark in it and a bleeping sound started. There is nothing wrong with the handbrake. The car had been serviced by a local garage a day or so before but this may be coincidence. As I drive it the "Handbrake On" light goes out almost immediately after starting off but the red circle stays illuminated continually. Also the bleeping will continue for five minutes and then stop provided, that is, I don't come to a halt. If I do have to stop, the 5 minutes starts again. This problem is driving me nuts. Any advice would be appreciated.
Thanks