Laptop suddenly extremely slow, now can't even start up

Yesterday my HP laptop suddenly started moving molasses slow. As in, even trying to type something in the start bar takes several minutes. I was able to start Windows but it took like 15 minutes to even get past the Windows logo. It's like everything is in slow motion. But task manager said the usage is at 0% or 1%. No programs are open. Trying to open folders, right-click on anything, or even move a folder results in the whole screen turning lighter (like a window does when it crashes) and says "Windows Explorer is not responding."

I've tried restarting and it says "Windows failed to start. A recent hardware or software change might be the cause." and recommends Launch Startup Repair. The first time I was able to launch startup repair, but it didn't seem to solve anything. Now it won't even launch startup repair, attempting to do so brings me to a new screen that says "Windows has encountered a problem communicating with a device connected to your computer." I don't have anything connected.

This apparently started when I uninstalled an old version of Gimp and downloaded paint.net. (But I didn't run the installer. The slowness started even before the download finished.) But it was fine yesterday.
I tried to open safe mode so I could run Malwarebytes but I can't open safe mode. Pressing F8 just makes it scream this high-pitched beep noise and takes me to the "Windows failed to start" screen.

This time when I tried to start Windows it brought me to a new screen: "Checking file system on C: one of your disks needs to be checked for consistency" Twelve hours later, it's still at 1%. It says "File segment record 41579" is unreadable" and says the same thing for every segment record number as far back as it's letting me see. It's taking about 20 seconds to scan each file, and it says "of 225792" so if it continues at this rate the scan would take 42 days! What do I do??

It appears your hard drive has popped a gasket. The first thing I would do is backup all user data, if not already done. You can do this in place by booting to a linux live CD and saving the data to a USB stick or external HD.

Then I would run some diagnostics on the drive. Check out the SMART attributes and run the long self-test. You can use gsmartcontrol or the drive's maker's utility to do this (seatools is excellent). One way is to tether the drive to a working machine via an external usb adapter, or to plug it directly into a tower.

If the drive is good it may be time for a factory Reset or a clean install.

Okay after about 20 hours it finally finished the disk check. I really don't know what the results mean, so I put pictures here:
Imgur: The most awesome images on the Internet

It then restarted as usual, but again in extreme slow motion. It took almost an hour from the Windows logo to the actual desktop. I've never seen it do this before yesterday. I can barely even open a folder.

paul1149 said:

Then I would run some diagnostics on the drive. Check out the SMART attributes and run the long self-test. You can use gsmartcontrol or the drive's maker's utility to do this (seatools is excellent). One way is to tether the drive to a working machine via an external usb adapter, or to plug it directly into a tower.

How do I do that? I can't do anything on this laptop because it's freezing non-stop. I have a Lenovo laptop with Windows 8 here, could I download gsmartcontrol on there and somehow use it on my laptop? Is there some way to tell if the hard drive is bad? I've never heard of this SMART stuff so I'm a little lost.

Right now the computer is up but I can't really do anything on it because it's moving so slow that it just keeps freezing.

A second laptop will usually need the usb hd adapter. They're cheap, but if you don't have one that's a problem. The alternative is to use a desktop, which will have extra hd inputs in the case. Or to use a boot disk that can run the diagnostic programs. The old Parted Magic has gsmartcontrol on it. You can run it on the Hiren disk's Win XP environment.

For the file system to be that hosed, something had to happen to the HD. Don't do anything else to it until you have backups of data.

Ok, I don't know why, but it seems to be back to normal speed now. I guess it just needed time or something? I still don't know what went wrong or why it's back now, and for all I know there's still a problem that's gonna break it when I restart. So I'm making a backup now, but it's gonna take a while. When that finishes, your recommendation is to download "gsmartcontrol", right? To check if the hard drive is damaged?

maybe chkdsk did its job. IAC, you're right to get backed up before any more work on the drive.

If you can boot up, I recommend Seatools for Windows to check the drive with the long test. I don't think it reads the smart attributes, though, so for that I would use either gsmartcontrol of defraggler.

*sigh* I thought it was back to normal. It was acting fine but in the middle of backing up to a external drive it cut off, restarted itself, and now all I can get it to say is "Boot device not found" "Hard disk not exist"

Imgur: The most awesome images on the Internet

So the hard drive is just dead, I guess. So what now? Do I just have to order a new hard drive?

I would still test the drive in another machine, because there could be a cable/interface problem in the HP. In fact, checking that the drive isn't loose, and cleaning its contacts, is a good thing to try. Hopefully you have your data saved at this point. Also, see if the drive shows in the BIOS.

I opened the back of the laptop, unplugged the hard drive and re-plugged it. I didn't see any dust or anything. When I turned the computer back on, it turned on normally at first but was still extremely slow, then flashed a BSOD for a second before going back to the "Windows failed to start" screen. This whole problem is going in circles.

I don't have a USB-to-hard drive connector to test it in another computer, should I try to get one, or is that moot now?

What do you mean by "shows in BIOS"?

edit: It went to the blue screen again, but this time I got a picture of it:
Imgur: The most awesome images on the Internet

I would, if you need to get more data off it, or to perform tests on it.

BIOS: hit Esc after turning machine on, then F10 I believe, to get into BIOS. See if there are any references to the HD. But chances are it's fried.