The drive has to be partitioned, but if it was previously partitioned and those partitions have now disappeared, it's possible that the drive is faulty. To find out if it's faulty, test it with the drive maker's diagnostic software that loads from a bootable CD. The links are here: http://www.tacktech.com/display.cfm?ttid=287
The DOS-based testing software will usually consist of an ISO file from which you can make a bootable CD using IMGBurn
Boot your faulty PC from that CD and the testing program will open.
Test the drive with the Long/Extended test.