well, you're on the right track if it takes 15 hours to install.
Open the bios setup and see what the power supply readings are, if available. Reset the bios to default.
first I would try Hiram's boot disk, or another type of disk analyzer and see if there is anything wrong with the drive or the sectors on the drive.
You may need to replace the drive or other parts.
here is a link to the manual:http://support.dell.com
remove the spaces from the above link before copy paste to browser window
But, it's obsolete, and you may decide not to put a lot of time and money into it.