|I don't know so I will guess.|
You need to boot from the OS install disc then delete all partitions including the hidden one then you shut down the PC for a minute or so (this will ensure the partitions are actually deleted. Next you boot up to your OS install disk then format and install OS.
If you don't delete the hidden partition as advised, the previous install may assume a refresher install and not change the platform from 32 bit to NTFS if you have changed from one to another. Also, previous problems could occur.
When the install is finished, you reboot and go to BIOS and change the boot order back to the Primary hdd Save and Exit and continue to desktop.
NTLDR referrs to the OS system loader which loads Windows.