In looking at the shutdown trace, it's being held up (at first glance) by clfs.sys - this, however, is just a victim. You can see what it "does" here: Common Log File System
Given that it's just a logging .dll, something is registering data and potentially logging during shutdown, causing this to show up as having a problem unloading - obviously, this is false, so after digging deeper, I found that the hpslpcsvc service was slow in shutting down, for almost exactly the same amount of time. This particular service gets installed by HP printers, so it looked suspicious. I also noticed that there's a driver delay, at around the same exact time as well, from AVG - specifically, avgmfx64.sys. Once that driver stops, the entire system shuts down (at least according to the trace), so I'm left with wondering which is causing the logging service to run like this - is it the HP printer driver service, or the AVG filter driver? According to the disk I/O graph, it appears that almost all of the disk access is going to "Unknown" (and at 100% utilization, from when the AVG driver loads to system shut down notification), but when looking at the file I/O table, the bulk of the disk I/O is actually FSCTL calls to \Device\HardDiskVolume2, by both SYSTEM and by a process called avgchsva.exe, which I would suspect being AVG's. I wish that was definitive, but it could still be an issue with the HP driver.
To cover all bases, it's probably useful to remove any HP software you have on the machine, and remove AVG - I would suggest you have downloaded the latest HP software for your printer(s), and the latest version of AVG as well before continuing - you might want to disconnect from the internet while doing this to be safe, so having everything local will be beneficial.
Remove the HP software, and AVG - then, reboot five times (needed for superfetch), and see if the problem continues. If it does not, add the HP software you just downloaded for your printer(s). Again, reboot five times, and see if the problem comes back. If not, I'd suggest adding the latest version of AVG back to the system and testing again (connected to the internet for the reboots at this point, of course), to see what happens. If the problem returns when doing this very drawn out test, you will have your culprit.
I usually recommend A/V software other than AVG, but to each his or her own - if it works for you, I'd suggest using it. However, it does have it's moments of causing performance issues, hence why I think your problem is the AVG driver and software, not the HP printer software.