Problem upgrading to Windows 10. The video adapter support from HP for this laptop is only up to Vista. Furthermore, the Nvidia adapter is not a standard one, so downloading a driver from Nvidia does not work, i.e. it will not run. After upgrading, you are left with only the Microsoft Basic Display Adapter. If you try downloading and running the HP video driver for Vista, it also won't run as it doesn't recognize Windows 10 as a valid operating system. This is particularly annoying since the Vista driver will run under Windows 10.
Here is the workaround:
Download and run the Vista video driver installation software from HP. The installation completes very quickly, and may look like it completes successfully, but it doesn't. Windows 10 will probably tell you the software may not have loaded correctly, but ignore the error and click through as if it worked. The driver installation should have been copied to your computer, in my case to a folder called "C:\swsetup\SP3780\WinVista64", but yours may be different. You can go to that directory and try to run setup again, but it still won't work.
To install the Vista driver, open control panel and start "Device Manager". Scroll down to "Display Adapter", and open it to reveal "Microsoft Basic Display Adapter". Right click on it and select "Update Driver Software...". Select "Browse my computer for driver software", and then browse to the folder where the driver is located, "C:\swsetup\SP3780\WinVista64" in my case. (Note: make sure you select the folder that is compatible with the 32-bit or 64-bit version of the operating system you are using. If you don't know which you are using, do a web search to find out how to tell.) Select next and the driver will install. It will take a minute or two to install, and the screen may flash or go blank during installation. Restart your computer and the Vista video driver will be loaded.
In my case, Windows 10 was able to find a driver for all other devices.