This web page at file.net may help. I appears it is part of the Sonic burning software and not part of Windows or a driver.

Thanks, but your reply is not quite correct. It is a device driver for the DVD drive, so I can't uninstall it without reducing the functionality of my computer. It came preinstalled on my system by Dell, which is why I'm hoping someone here has a suggestion for how to resolve the problem.

Thanks, but dismissing the message doesn't fix the underlying issue. I'd like to enable memory integrity on my system, if possible.

Hello, a recent Windows update caused that.  The message must be coming from Windows Security formerly known as Windows Defender.  There is an option to dismiss it, select it and the Device Security will be enabled again. 

From what I understand, memory integrity is Off by default.  Sometimes, Windows updates triggered to turn it on, hence the report of incompatible driver(s).

To turn on memory integrity:  a).  your device must meet the requirements for standard hardware security such as UEFI, TPM 2.0, and Secure boot, they all must be Enabled.  b).  any incompatible drivers must be resolved.

Do you know if this core isolation feature on your machine has been On or Off all this time?  If you really want to turn it on but the slider button won't work, you can use Registry Editor.  But when you use the device with incompatible driver, it may resulted in BSOD.  Therefore, I suggested to dismiss the status and don't worry too much about it.

To enable memory integrity using Registry Editor:

1. Press Win+R to open the Run dialog.
2. Type regedit and hit the Enter button.
3. Click on the Yes option.
4. Navigate to Scenarios in HKEY_LOCAL_MACHINE.
5. Right-click on Scenarios > New > Key.
6. Name it as HypervisorEnforcedCodeIntegrity.
7. Right-click on it > New > DWORD (32-bit) Value.
8. Name it as Enabled.
9. Double-click on it to set the Value data as 1 to enable and 0 to disable.
10. Click the OK button.
11. Restart your computer.

Note:  I share my knowledge and providing help with best intention.  Any work on your machine will be at your own risk.  Always back up your system before attempts. 

Search the Roxio support website, for 'PxHlpa64.sys' and it finds this article 'Roxio: You cannot enable the Windows Memory Integrity feature because PxHlpa64.sys is not compatible'. That article explains the issues and you can download it at a .pdf file.

Unfortunately, it doesn't seem to contain a useful resolution. ("You will need to determine which disc burning program is using this PxEngine system file, then either uninstall it completely or reach out to the software developer for a version that is compatible with the Windows Core isolation feature.")

@lat002  Yes, I know which app it is. Only Sonic's CD/DVD burner program uses PxHlpa64.sys on my PC and it's digitally signed by Sonic.

So far- there currently are no updates available to resolve this problem. I'm just going to keep using it and not worry about Core Isolation.