What may be the issue with external hard drive on USB?

I have a 160GB Western Digital USB external hard drive. Some times it ‘behaves’ quite normally, but at most of the times, it disconnects itself from the port very frequently, and many times it also gives the message for formatting the drive! Sometimes, the computer also fails to recognize the existence of the drive. After taking out and putting in the USB cable 2/3 times, the drive becomes active. And once active, 99% percent of time the working becomes quite smooth.

What is the problem, and how can this be overcomed? Is there any USB version problem? Is there any chance of physically damaging the drive, and thus loosing my important data? Please answer at the earliest.

– Sayef Hussain (sayefhussain@yahoo.com)