Here is what you should do. Look in control panel (CP) to see if any of the programs listed in the link below, appear as an entry in CP.
http://www.carrona.org/pxhelp20.html
If you can't find any of them, that means that the program related to, or associated with
PxHlpa64.sys may have already been uninstalled, leaving behind, just the driver and possibly registry entries.
Download "autoruns" and use it to locate and disable the driver, after making certain that all Microsoft entries have been hidden, to eliminate the possibility of a mistake.(instructions in the youtube video link below.)
Autoruns for Windows v12.03
This utility, which has the most comprehensive knowledge of auto-starting locations of any startup monitor, shows you what programs are configured to run during system bootup or login, and shows you the entries in the order Windows processes them. These programs include ones in your startup folder, Run, RunOnce, and other Registry keys. You can configure Autoruns to show other locations, including Explorer shell extensions, toolbars, browser helper objects, Winlogon notifications, auto-start services, and much more. Autoruns goes way beyond the MSConfig utility bundled with Windows Me and XP.
Autoruns' Hide Signed Microsoft Entries option helps you to zoom in on third-party auto-starting images that have been added to your system and it has support for looking at the auto-starting images configured for other accounts configured on a system
http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx
How to use Autoruns.
https://www.youtube.com/watch?v=HhtSDsQYi28