From my experience (with XP), if CHKDSK runs frequently on a partition/drive it is a sign the drive is on its way out. Mine did this with a Maxtor drive for some time before the drive simply failed when carrying out tests as detailed by the Support team at Maxtor.
Drives are generally reliable but have been known to fail at an early point in their lives. The fact you have had ‘rattling’ could easily indicate drive imminent failure and added to CHKDSK running at startup is not a good sign.
Given the age of the PC (six months) I suggest you get onto Dell for a repair.