Sporadic hard drive intensely busy, apps stop responding

Man, this is frustrating. I've spent hours and hours searching the Internet and I cannot find anything matching the description of my problem. I'm running MalwareBytes in hopes of possibly finding some malicious culprit, although I expect it is unlikely since this didn't crop up shortly after installing anything. Unless there was a timebomb waiting. But again, couldn't find anything suspicious looking in the running processes, nor in temp files.

Malware bytes completed... found some minor stuff in a Google Chrome extension, but that's it. Rebooted. Ran Event Viewer... triggered the hard drive endless loop again.

So I'm going to attempt a system restore to an earlier point, before this all started. Can't hurt to try...

EDIT: I guess it CAN hurt.

Well, the hard drive repetitive loop is now happening during boot-up, which is increasing the time to boot up by nearly a factor of 5 times. Previously, it would only happen after the desktop was initialized.

I'm guessing that there's something wrong with the hard drive and for some bizarre and unfathomable reason, the disk utilities are unable to detect it.

When a hard drive is starting to fail, there can be a number of symptoms. But typically from what I've seen, hard drive diagnostics will show that something is wrong. There may be certain functions that just don't work because system files have been compromised. Or a detection of bad sectors that repeats. Or peculiar loud noises coming from the drive. Well, you can add one more to the list. The drive gets into this perpetual loop of activity, which has a pattern of sounds that repeats. Nothing loud, and sounds like normal drive activity, except that it just doesn't stop. Or... it'll stop but then start again. And when it's going, applications become slow and throw an unresponsive status.

When this first started to happen, I figured it was software that was causing this. Malware Bytes didn't turn up anything nasty and anti-virus has been running without incident. Hard drive checks turned up nothing. I'd reboot in safe mode and it would still happen. I just couldn't figure out the cause. So, I decided I'd roll back to an earlier save point, prior to when the symptoms started. This actually made it worse, because it seems as though that level of intensive disk activity exacerbated it. Now instead of it happening only after the computer was done initializing, it is happening during boot-up... which makes it take MUCH longer to start up. I was able to run a BIOS level diagnostic just before start-up (something that HP provides on their computers) and while the check ran through without throwing any specific errors, it did warn me that disk space is full! And it's obviously not.

In short, my drive is failing and my computer is now unusable (thankfully I have a backup computer). Now I have the unfortunate circumstance of having been "late" on doing a recent backup and must try to mound the drive via USB to pull off data. This computer is only 3 years old. I've had laptops for many more years than that without any hard drive failures. Very peculiar. Well, my next one is going to be SSD!