Why WinXP makes change in boot sector at each boot?

[Crux Crux]

Each day when my machine runs the scheduled AVG whole system scan, it
finds that the boot sector has changed. Prior to the boot there is a
delay of some 20 to 30 seconds showing the "Enter Setup" screen. When I
press Del to enter BIOS, again there is delay of many seconds. What
could be the problem with the system? My harddisk had developed some
serious problems and I had thought that it was irreparable, as XP
failed to install or format it. However, I was able to format it using
Gparted of Puppy Linux. Anybody has any idea?
Thanks in advance for any advice.
Regards
Cr___X

 

[smlunatick]

If XP could not format or install on your hard drive, without using a
Linux, I would replace the drive immediately. The hard drive is or
will be failing soon!!!

As for the "Enter Setup" and the boot sector change, I would also check
and replace the CMOS/BIOS battery (usually a coin cell type -- like a
watch battery.) These problems may all be related together.

Locate the hard drive manufacuture's web site and download the hard
drive diagnostics. Run the diagnostics so as the how far the hard
drive problems have "evolved."