windows 7 - Constant freezing on laptop even though plenty of system resources

I bought an Acer Aspire 7560 with Windows 7 installed a couple years back. It has 4 GB of RAM and a 1.4 GHz processor with four cores. I've always had problems with the laptop freezing during seemingly simple tasks (i.e. using the file explorer), and I assumed it was aero causing issues on such a low-end laptop. I recently installed Windows 10 in hope that the new OS would solve the problem, but it didn't. I took a closer look and it's freezing when there are plenty of system resources available:

Any given program of mine will freeze whenever I do something like open a menu/tab, click a button, etc, but it seems to happen in waves where I'll have issues for a while, and then it will be completely fine at other times. When one program freezes, it will stay frozen for maybe 30 seconds, but other programs continue working fine (I can hover over and see url underlines, tooltips, etc), but if I start interacting with any other program a bunch, they will freeze too. When more programs are frozen, it takes significantly longer for them to recover. The symptoms make it seem like I don't have enough system resources, but I watch my system performance with the task manager like in the screenshot, and my CPU/RAM usage never rise to significant levels. I have enough resources, so why does my laptop freeze like this?

Edit: When I installed Windows 10, I wiped everything from my old install of Windows 7, so the issue won't be something leftover from there.

Edit: SMART test results:

The task manager says 50% of my hard disks are being used (100% C:\, 0% flashdrive), but the items listed in the task manager don't add up to that:

What in the world is using the harddrive that much? This is a clean install of Windows 10, and I think the only thing that might have carried over are the Windows 7 drivers. I selected "erase programs and files" from the Windows 10 updater, so I shouldn't have anything from my previous install of Windows 7 that could cause this.

Answer

according to your screenshot, it said it is your harddrive problem
Disk 0 (C) fixed at 100%, try check on Processes tab which process has the highest disk activity

also, you can try defrag your harddrive