MBR:\\.\PHYSICALDRIVE0\Partition4 Please help!!!

Hi,

First, thank you so much for reading this.

So I’m going to piece together the chain of events as best I can, because it all kind of happened quickly.
I have avast internet security and, of course, I run a full scan at least once a day and usually a smart scan as well–including earlier this evening, which came up clean as usual.
However, I was sending an email in gmail and as soon as I hit “create new email” (at least that seemed to be what happened and I didn’t have any other browser tabs open) an avast pop-up came up. It flashed away too quickly for me to see what it said (and I looked at the “what to do if a file is infected” thread, but I can’t figure out how to access the last popup. I just can’t find that option for some reason–I went into “notifications,” which had something that said “threat blocked” that I thought was it, but it just had a button for the virus chest, which appears to be empty), and then launched into smart scan, which identified this virus. I’ve tried repairing it, deleting it, moving it to chest and nothing takes. For instance, when I go to delete it, I get “Error: the handle is invalid (6)” and when I hit move to chest, I get “Error: the request is not supported (50)”
I did a little googling, but to be honest I don’t really understand much of what I found on forums and the only thing I remember from dealing with malware/viruses in the past is that using Delsym (I think this is the name of the program?) has been effective.
For contextual information: I’m running Windows 10. Additionally, I don’t really go to insecure sites online (that is, ones that avast tells me are unsafe), so I don’t know how this happened in the first place. I even checked chrome to see if anything had downloaded (it didn’t show anything–but I could be looking at the wrong thing. I just clicked on “downloads” under History) and looked at my web history, just to see where I’ve been today, and it’s all normal: just email, modcloth, cracked.com, youtube, etc.–all sites that I’m familiar with and trust and have gone to a thousand times.
Also, I’m currently running a full scan (which already shows that it’s found something, which I’m assuming is the same thing), but I thought I should post this sooner rather than later, because this is really freaking me out and I need my computer to work (I have an enormous amount of work I need to do tonight, for instance, which is impossible without it).
Additionally, I’ve run Malwarebytes, but that scan didn’t find anything at all and came up clean. I’ve attached that log (as a .txt file–I hope that’s right)

Thanks!!! I really appreciate any advice or help that you can give me!!!

I’ve run the full virus scan and a whole host of new things came up. For the most part, avast seemed capable of moving them to the chest or deleting them (apparently at the next reboot, which I am afraid to do because I don’t know if the computer will start up again or what to expect).
However, one did not vanish:
C:\Windows\System32.…\BBl{1cc41df4-4b1b-11e6-80cc-e41d2d1026d0}.TMContainer000000000000000000002.regtrans-ms
(I might have miscounted the zeroes in the last bit while transcribing it, just fyi)
When I tried to delete or move it to the chest, what came up was Error: the system cannot find the file specified (2)

Since I can’t really transcribe all of these, I took screenshots of the scan details, attached below.

There was one more screenshot for the same list, here attached: