Hi and welcome to TSF...
The best thing to do would be download the hard drive manafacturer's diagnostic tools then create a bootable cd/floppy which you can then use to perform some health checks on the drive.
Also, if you download and install a freeware program called SpeedFan, you can use the S.M.A.R.T tab when the program is running so you can find out more information on the general health of the hard drive.
Hope that helps :)
p.s - In the meantime, it would be a very wise idea to backup all the data you want to keep from the drive as these kinda errors can sometimes mean the drive is on it's last legs :)