Installing an unsigned driver might cause an error in the Altera SDK for OpenCL running on Windows 8.1

If you run the Altera SDK for OpenCL version 15.1 on Windows 8.1 and you install an unsigned driver, you might encounter the following error messages:

difx_install_preinstall_inf: err e000024b, last event 0, last error 0. UNKNOWN

difx_install_preinstall_inf: err e000022f, last event 0, last error 0. UNKNOWN

Prior to installing an unsigned driver, disable driver signature enforcement by performing the following steps:

1. On the Windows login screen or under the Charms bar, open the power options menu.
2. Hold the Shift key while you click Restart from the power options menu.
3. After your computer reboots, select the Troubleshoot option.
4. Select Advanced Options.
5. Select Startup Settings.
6. When prompted, click Restart to reboot your computer.
7. When the Startup Settings menu appears, press the F7 key to choose the Disable driver signature enforcement option.

After your computer restarts, you can install unsigned drivers.