Help for external SATA hardisk.

Hi, my 250GB Seagate Barracuda 7200.10 ST3250824AS SATA hardisk which is put in a external USB casing just have some problem. When I power on the hardisk, there is no hardisk detected. The hardisk sound as if a cd-rom that can't be able to detect a cd. After 5-10 minutes, then only each partition on the hardisk appeear. There are 3 partition on that hardisk but the first partition only show as local disk without the original label and it is blank although there are many files inside. Other partition are okay.

I try to resize the first partition from 100GB to 99GB and then it start to work normally even after I resize it back to 100GB again. Then I run scandisk on this partition and there are 4kb of bad sector. My questions are:

1. What could possibly the cause of this problem and does this hardisk still can be consider reliable?

2. This hardisk is only 1 years old and still under warranty, can I get a replacement because of the bad sector?

3. I tried to run mhdd using the magic boot disk with usb support. The hardisk is detected but when scan, it just stop at there. Any idea?

Thanks.

The easies way is to get one replacement of the disk if you don't want data in it.