General :: Deleted Files - Free Memory Didn't Increase?

I have a Samsung Galaxy Tab 7.7, though I've seen people post about the problem with other devices, so I think this is an "Android" problem.

I just got the tablet about a week ago, but this is by no means my first tablet, or Android device. I don't want to root or anything -- I'm happy with the stock device, along with the apps I install and the files I download to it. I've got a 64GB microSD card (also Samsung brand), formatted as FAT32, and it works just fine.

So, I was filling the tablet up with media files, and I was downloading video files to it. It has 16GB of internal memory, and I figured I would fill up a bit more than half of that with some of my bigger video files. I downloaded a few files, then figured I could download a bit more, and downloaded a couple more. Then I looked at the free memory, and it was down to 3GB free -- "whoops, too much." So, I deleted the two files, which were about 3GB together. AND THE FREE MEMORY DIDN'T INCREASE ONE BIT.

And I've been trying to "get my memory back," ever since. So, here are a couple of screen shots I can show you:

First up is the usual Storage view:

OK, so what the heck is that 3.36GB in "Miscellaneous files?" That's roughly the size of the two files I deleted, so let's go in and take a closer look:

So, it's in the "System memory" up at the top. So, what is "System memory," and what could be taking up that kind of space? Some kind of "cache" that kept the two files I deleted in memory, perhaps?

So, from here, it's pretty simple: What is in that "System memory," and how do I clear it out?

It's NOT any "application cache" -- I've used apps that clean out the application cache, but they didn't touch this "System memory."

I've tried the "Wipe cache partition" from the recovery menu, and that didn't touch this "System memory."

I sure haven't seen any apps that can do it.

Or, is having a big wad of whatever in the "System memory" pretty typical, and thus it doesn't have anything to do with the fact I deleted those files and the free memory didn't increase? I doubt that, because I've seen quite a few screen shots of the Miscellaneous files screens that other folks have posted, and I have NEVER seen a "System memory" item at the top like I have.

At this point, I'm expecting that I'm going to have to do a full reset to the factory build, just to free up this big wad of unused memory. Of course, I would rather not do that, but if I'm going to do it, it would be "better sooner than later."