My C: drive keeps filling up automatically

I’ve gone ahead and scanned my computer using Malwarebytes Free, CCleaner, AdwCleaner, and Avast Free, and according to all of them, there isn't a single virus to be found.

The thing is, my C: drive just completely filled up right after I ran a scan with CCleaner, and now every time I reboot, the available space fluctuates wildly—it can't seem to decide how many GBs are actually free. Because the numbers change every single time I turn the machine on, I'm starting to suspect I might have a virus hiding somewhere, but I honestly have no clue which program I should use to actually fix this.

Here are some screenshots, if they help clarify anything at all: http://s23.postimg.org/qop7034zv/cdiskproblems.png

My Recycle Bin is totally empty. I’d love to just go in and delete about half of these files with those bizarre, nonsensical names, but I’m terrified of accidentally breaking something important.

Am I dealing with a virus here, or is everything actually fine? And if things aren't fine, what am I supposed to delete?

I tried Googling the issue, but most people online just suggest installing some heavy-duty analytical software to figure out what needs deleting, which doesn't help me one bit since I don't even know what I'm looking for in the first place; those programs just end up making me more confused.

EDIT: Now, after a little while has passed, it's reporting yet another different amount of free space: before http://postimg.org/image/7y1ieedih/
after: http://postimg.org/image/tisaw8gxh/

Is System Restore turned on?

I’m honestly not quite sure how System Restore could even be turned on right now, but if you want to double-check, here is how you can verify that.

So, I finally went ahead and disabled System Restore, and suddenly I’ve got 9GB of space back. I guess that's my grand solution to the problem, isn't it?

Most likely, yeah. If you really need System Restore, go ahead and turn it on, but maybe try shrinking the file size a bit...

Uh, thanks.

You aren't the only one facing this. There are probably 500 million people dealing with the same thing...

There are several possibilities...

I will give you two main reasons...

1. Windows updates. They run constantly. Some users end up with 50GB or more just from that. Look in the folder c:\Windows\winsxs\
Turn off automatic updates and this nonsense stops. I have used Windows for years and never allow automatic updates... I only perform manual ones when necessary for things like Adobe Flash Player, Java, or similar junk for Mozilla Firefox...

2. Junk accumulates in the Temp/Tmp folders and nobody ever clears it out. It adds up quickly. You need to empty it manually. It isn't difficult if you know where to look. Put a shortcut on the Desktop and check it at least once a week.
Alternatively, get CCleaner; it handles the cleanup automatically for anything older than two days...
For example: c:\Users\Administrator\AppData\Local\Temp\ or, if you aren't an Admin, check whichever user folder applies to you.
And
c:\Windows\Temp\

Take my Windows 7, for instance. I once created a 27GB Partition
and I still have 11.6GB free. I don't keep any junk,
aside from that 4GB mess in c:\Windows\winsxs\
I haven't tried deleting that yet. Some files in there are necessary, and Microsoft claims you shouldn't touch them—though some people do.
Could it cause problems? Microsoft says so. I doubt it. It seems more like Spy tactics to me. Since it isn't taking up much space on my machine, I haven't touched it, but if I had 10GB or more tied up there, I wouldn't wait. I might tackle it eventually. For many people, that folder hits 25GB or more...

Anything that consumes space, like photos or music, goes straight to the D: drive.
That keeps the C: drive small, allowing for a fast Backup and Recovery (it takes about 10 minutes), using an external program rather than the built-in Windows tool.

Good luck.

Thanks, though I actually ended up clearing out everything in the temp folder later yesterday. 🙂