Thanks to Fabian for informing me of the risky nature of Dev-Host, prompting this much-needed update.
I experienced the same issue, and thought I'd try reinstalling old drivers to see if that helped.
Solution/permanent workaround
A more permanent solution taken from the answer posted by Anonymous, reformatted with pictures shamelessly taken from this article on HowToGeek.
The short version solution of this is: disable driver signature enforcement and then install the latest Synaptics driver.
Disabling driver signature enforcement
Press Win+I, or open up the Windows Charms bar from your right upper/lower corner and select "Settings".
Select "Change PC Settings" from the Settings-part of the charms menu.

In the Settings-app, select "Update & recovery".

Then, choose "Recovery" from the same left-side menu.

You'll get the following display, where you'll need to restart your computer to continue, which will happen when you select "Restart now".

Now, once restarted, you'll need to select "Troubleshoot" as the option on the startup menu.

Head into the "Advanced options".

Then to the core of what we're looking for: "Startup Settings"!

We'll have to do another restart, as we'll be modifying options that are applied at boot.

At last, now you'll have to press F7 to disable driver signature enforcement for this boot.

When your computers has booted up, you'll need to install the Synaptics touchpad driver, and it should complete without issue.
Once installed, it's highly recommended that you restart your computer one last time.
In the event that it doesn't seem like the touchpad driver is in use, you'll need to manually change the driver for your touchpad device. Here's a quote from the other answer:
If the Synaptics settings does not appear under Mouse properties after completing the preceding steps, try the following:
- Open device manager
- Find the touchpad device (“PS/2 Compatible Mouse”)
- Right click on the device and click “Update Driver Software”
- Select “Browse my computer for driver software”
- Select “Let me pick from a list of device drivers on my computer”
- ncheck the option “Show compatible hardware”
- nder “Manufacturer”, scroll down to “Synaptics”
- Under “Model”, the 17.0.19 driver should appear.
- Select the driver and click next.
- Click “Yes” to the “Update Driver Warning” pop-up.
- Restart
Cause of error
It's worth noting that it seems like it failed due to not being properly signed. When attempting to install just the driver, manually, from the device management console, it would allow you to select it, but would fail due to not being digitally signed. It's an odd peculiarity that I hope gets fixed relatively soon.
Previous workaround
The following steps are not recommended, as they use older versions of Synaptic and needs to be downloaded from less-desired locations.
Another fellow troubleshooter already had the issue, and found an older version of the suite, v17.0.6.13, which used to be available, but the host is down.
Simply installing this version, after making sure I had uninstalled previous versions, can "solve" the problem.
Note: Here are two alternative version. Be careful with the download links on the sites, as some ads might give you unwanted software: Link 1: recommended | Link 2: careful!
The first step is we need the installation log file that provides us more information other then simply "it failed". – Ramhound – 11 years ago
Locate Synaptics.log – Ramhound – 11 years ago