I have looked up the info on your PC:
Dell born on date: Dec 8th 2004
Hard Drive born on date: Oct 17th 2003
With that age of the Seagate drive I want to test it first. Nine years is like dog years for a hard drive. Five years is a typical lifespan for a desktop hard drive. Some last longer some don't make it to five years but they all degrade over time and die.
Follow the instructions from the previous post to remove the drive being sure to note the orientation of the power and ATA cable before removing. The cables and drive are keyed to mate one way but I've seen people force them anyway and break things.
The drive will need to be attached to the workstation you will test with. You will need a way to interface the drive with the workstation. Something like this
would work best.
I want you to download and install HD Tune
to test the hard drive with.
This would also be the time to copy your personal data, which I'm sure you have a lot after 8 years, to the working PC.
When you get to the HD Tune page, scroll down to the second selection hdtune_255.exe and download and run the program.
Click the drop down and select your 80GB ST380011a drive. Click the health tab then click the copy to clipboard icon at the top of the window. Paste this information in your reply to me. Next click the error scan tab then click start. Let the scan finish then click the copy to clipboard again and paste the results in your reply.
If you don't feel comfortable doing this on your own you will need to enlist support from your IT friend.