Does that mean this update will finally install? I've tried three times, had it fail all three times, and have resorted to hiding the update.

This was posted on the Insiders Forum:

Hi everyone,We recently released an update for the Windows 10 Technical Preview (Build 9879) to fix
an issue with frequent Explorer.exe crashes - KB3020114. We’re releasing a few fixes to
the most painful issues hitting Windows Insiders on this build since we won’t have a
full new build until early 2015, and we want to keep it usable for you through the end
of the year.

Unfortunately, as many of you discovered there was a problem that affected about 12% of
PCs when installing this update, causing the install to fail.

The issue occurs due to 2 underlying bugs:
1. In build 9879 we introduced some new System Compression code that systems with
SSDs can take advantage of to reduce disk usage by the OS. In some cases the logic for
low-space detection gets inverted, and we compress automatically as a background
operation.
2. On PCs have had system compression enabled, an additional bug with how the
filesystem tracks deletes caused the installer to think that the temp files failed to
extract correctly, so the installer fails because it thinks it cannot complete.

Workaround

For the short term, anyone affected by this can get past it with the following
workaround:
1. Restart your PC
2. Open CMD.exe as an Administrator and run: compact /u /exe /s:%windir%\winsxs
\filemaps
3. Immediately afterwards run Windows Update and Check for Updates
4. Install KB 3020114
5. Restart when prompted

I did this on my PC, but I switched over to an HDD after I got fedup with the daily CHKDSKs on the SSD. When I get a chance, I'll image this install to the SSD and see if this KB fixes the daily filesystem corruption problems.

John Pombrio said:

The only hassle I have now is that the hard drives spinning down after a few minutes of inactivity so it takes them a while to respond. I have hard drive set to sleep never in advanced power settings. I use KeepAliveHD to "ping" them every 4 minutes to prevent this.

Are your drives internal or external usb? My external usb drives take a long time to wake up. I use NoSleepHD set to 10 minutes to keep my drives awake. I think it's something in Win 8 and Win 10. I don't remember having this problem in Win 7.

Hi there

This "Fix" seemed to have broken the USB driver on my 9879 VM -- now I can't add / remove any USB devices to the VM after it is powered on. Undoing the fix repaired the problem.

So I think this fix does "more than it says on the tin". It doesn't only "Fix IE" but obviously alters other stuff as well.

On a NON VM (a real machine) the fix might be OK though. However I do know a lot of people are also running these builds in various states of "repair" or "disrepair" as VM's so anything is likely to happen when installing these fixes.

Cheers
jimbo