Help, Help, Please. PC Won't Start.

Hello,

Have a 2 year+ HP Desktop.

Last evening, it started to run Incredibly slow.
This morning, wouldn't open up, at all, other in Safe Mode.

Runs just fine in Safe Mode; internet works fine.

One of the HP diognostics I ran came back with HD ST31000528 AS
Failed. I assume that this is the regular internal HD on my PC.
Is this likely what it is ?

But, again, everything looks just fine in Safe Mode.
Isn't the HD required for (most of) the Safe Mode operation ?

Don't want to dump the PC, or try a new HD if I don't have to.

What else in the way of diognostics, etc. can I try ?

Don't remember the exact line, but isn't there something like:
RUN: msconfig, or something like that, that I seem to remember helped out a year or so ago. Was a very big, long time scan, but it did find and fix things.
What might I be thinking of, please ?

What should I do next ?

Any help would be most appreciated.

Thanks,
Bob

I would Check the hard drive with the manufacturer's diagnostic tools.
Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp.
HD Diagnostic

For Seagate download the Dos ISO from here:
| Seagate

Burn the ISO to CD, boot it to run the Extended Scan which can diagnose and repair your HD.

Afterwards run a full Disk Check if necessary from System Recovery Options Command Line: SFC -SCANNOW Run in Command Prompt at Boot

These two procedures can return a failing HD to service, or diagnose it with certainty.

Once HD is repaired or checks out OK then if neceesary work through these troubleshooting steps