This word wall is necessary to gather all of the information.
Basically, my HDD was physically failing, so I bought a new one and cloned the failing one.
It's been working fine for about a month now.
A day or so ago I put the PC into 'Hibernate' mode. (I hadn't done this since I started using the new HDD)
When I woke up, it was booted onto the old HDD (I had forgotten to change the boot priority), and it was using 100% disk for ages. (not exactly normal)
At this time I didn't realize it was the old HDD, because of it being a near exact replica. So I used it for half a day, everything was working fine.
Once I did realize it (missing projects and such), I booted into the new HDD.
Once using the new HDD I started finding a ton of really small, seemingly unrelated bugs. Chrome wouldn't stop erroring, all chrome icons were missing, some things wouldn't launch, etc.
Though, everything else was fine. Steam, Discord, Photoshop, Cinema 4D, and video games all ran fine. So I don't think it's a hardware issue.
I assumed something had gotten corrupted because of it being put into 'Hibernation' and not being re-launched properly.
So I woke up today, and now no browsers will launch, but still all of my programs are working fine.
I turned the PC off to run a chkdsk and virus scan (I haven't downloaded any programs in weeks, though) and when it booted, I got the error in the title.
The operating system could not be loaded because the digital signature of the file couldn't be verified.
Error code: 0x0000428
It sounds like a virus, except I have not downloaded anything.
I have no idea what caused it, but it was working fine until I put it into Hibernate mode, which could be completely unrelated.
Edited by microk, 25 April 2017 - 06:56 PM.