Boot issues / PC won't boot

Just turned on my PC and it hung during boot. Here’s a photo. It just sits there. I had to restart a few times before Windows finally loaded.
The keyboard wasn't responding at all. The only thing I noticed was a change in the MHz reading. Usually, it's 450, but here it shows 442, and the numbers in parentheses look different than usual. When it boots successfully, that number stays at 447.

Everything looks fine once I'm actually in Windows. But when I check the CPU stats in Speccy, that multiplier keeps jumping around.
Temperatures seem okay. My GPU is running a bit warmer than the rest, but nothing out of the ordinary. Windows isn't flagging any errors.

I haven't run into anything like this with this rig before.
Not sure what else to add.
Even though this setup is getting older, surely the processor isn't about to die on me, right? 🙂

edit: Just shut it down and restarted; it booted into Windows without any issues this time.

🤷

Check the date too—it looks like your 3V CMOS battery is totally dead. When that happens, you lose everything in the BIOS, not just the clock, but all your other settings as well.

Is it the motherboard battery?
My PC hasn't even acknowledged its existence for a while now. Every single time there's a power outage or something similar, I have to manually reset the date in Windows. I'm not really sure why. At first, I assumed the battery had just died, so I popped in a new one, but the issue persists. It’s been like this for years.
Everything is running fine for the moment. We'll see...

So here’s the deal, I think my hard drive or maybe the motherboard decided to just quit on me entirely, because when I fired up the PC, I got hit with this:

reboot and select proper boot device or insert boot media in selected boot device and press a key

I grabbed a USB stick with Windows on it and it actually booted up fine, and when the installer popped up, it gave me an option to run a repair—and being the absolute genius that I am, I went ahead and clicked it, and now I'm staring at this mess:

Windows failed to start. A recent hardware or software change might be the cause.

To fix the problem:

1. Insert your Windows installation disc and restart your computer.

2. Choose your language settings, and then click "Next."

3. Click "Repair your computer."

If you do not have this disc, contact your system administrator or computer manufacturer for assistance.

File: \Boot\BCD

Status: 0xc0000098

Info: The Windows Boot Configuration Data file does not contain a valid OS entry.

I even tried pulling the CMOS battery out thinking maybe that would reset something and let me boot, but nope, absolutely nothing.

Someone please help me out here!

Look, if you're running Windows 7 x64, you aren't going to be able to run a repair using an install disc from Windows 8, Windows 10, or even Windows 7 x86. It just won't work like that.
First thing's first: double-check your hard drive cables (just make sure you don't swap the SATA ports around). If that isn't the issue, you’ve probably got bad sectors on the drive. But before you start running any deep scans, try plugging that drive into another PC and grab all your important stuff—photos, docs, whatever—while you still have access to them.

Look, I’m not even trying to run some kind of repair job here, I just want a clean, total reinstall

But seriously, I have no clue why this thing won't just clear out and go away