Why is my laptop showing smart hard disk erro

The reason the BIOS is doing this is HP and Dell laptops have checked the SMART data at the firmware level for many years - when these errors show on HP and Dell BIOSes, the drive is failing. You'll need to backup the machine to an external drive and replace it to clear the POST message. I wouoldn't reuse the drive when it has SMART issues -- once you get a SMART error, the drive is on life support. Use something like DBAN to wipe the old drive once you backup the data and move everything over and you'll be good, but it can take a minute unless you opt for a more quick erase method.

Get a good 512GB SSD (SATA) when you replace the drive -- the cost of SSDs has come down drastically in the last several years -- Something like this is so inexpensive it doesn't make sense to install another spinning drive. That being said, this laptop will not run Win11 so unless you plan on switching it to something like Linux once October rolls around, I'd probably consider a new laptop after 12 years. This guide covers how to replace the drive.

It doesn't have to be brand new. A nice EliteBook 800 series with an 11th or 12th-generation Intel (or similar AMD-equipped 8X5 model) chip is cheap enough these days. I would put a cheap SSD like the Samsung in this laptop and let it live out it's final days on Linux, get an EliteBook 840 that just left warranty with an 11th or 12th gen motherboard (or an equivalent AMD-based 845), throw an SSD and 32GB of RAM in it, and semi-retire the old one. If this were my laptop, I'd grab 2 640 or 645s in the G9/G10 trim (12th gen Intel/Ryzen 5000 on G9, 13th gen Intel/Ryzen 6000 on G10). These are slightly less capable 800 series machines but have built-in Ethernet - HP dropped it on the 800 after the 8th gen 800 machines). Buy the G9 right, and it can generally be bought for $200-250 (16GB/256GB SSD) as a base, $250-300 with 16GB/512GB SSD. At that point, installing a a 1TB SSD and 32GB of RAM in both. GRANTED, I can buy such a machine at a nice discount with negotiation and nonsense snafus like getting a base 256GB SSD+16GB, then install Win10 and upgrade it later to 11.

The only other "real" potential loss is the 600 machines POTENTIALLY not getting the internet-based SureRecover option. It works on my G9, but in the past, the feature was only found on the 800 series. The other potential "loss" is HP Wolf Security - again, my 640 has the option but it's less common on the 600 series vs 800 series as it's a BTO option or part of the purchase price with the same length as the warranty. 32GB USB drives are a thing, so I wouldn't cry over this being a potential omission -- but know it's 100% not present on the ProBook line.

I wouldn't worry about the Wolf Security software because it's enterprise endpoint security SW that means nothing to me and you on the outside. The machines get decommissioned and are no longer managed, and if the sysadmin is smart, they get blocked from accessing the internal corporate network. If it works, it may or may not be useful—YMMV.

The reason I can LEGALLY downgrade an 11 Pro Machine to a 10 Pro is downgrade rights -- I've used it before to deal with Vista Business on the Dell D and E series because those things mostly shipped with XP, but some have a Vista license (and we all know how bad Vista is).