Then I guess it's safe to assume that the pop-up you received and sound you heard were indeed coming from the HP Support Assistant program And if you have the HP support assistant settings as defaults then you will get such pop-ups from HP
Once you have done this your machine should though posting the lists of processes and services running will help me to be sure be in the same state as my HP machine, which has HP support assistant installed should I ever need it but disabled so it doesn't run in the background, update itself or cause pop-ups We greatly value your business and appreciate your ongoing patience as we work to get your order to you

Contact HP

After installing CCleaner you should use it's options to disable it's background running.

In Window HP Support Assistant Alert (or is it an Alert Lookalike?)
1: This version of Windows running with the processor or chipsets used in this system has limited support from Microsoft
HP Customer Service Rating 2020: Undercover Tech Support Review
exe by the same method
Contact HP
Type those names into a post on here
The most popular versions of the HP Support Assistant are 8 The type of media it makes are absolute last resort ones full factory refresh, wipes your files, programs, system settings, everything and system images should be used instead where possible, but these media are worth making
At this point you should find there is one HP related process running in the task manager's process list, and one HP related service running under the task manager's services list the process and the service should be named HPWMISVC, If I remember correctly, I'm not on an HP machine right now so can't check right now You can update your drivers automatically with either the FREE or the Pro version of Driver Easy

HP Customer Support Software and Driver Downloads

Any time you open the HP support assistant program from the system tray button you should go through the steps above again, some of the things you disabled might stay disabled others will need you to re-disable them.

HP Laptops for Home and Business
Back again I was browsing the internet and received an in-window pop-up that looks exactly like an HP Support alert - it made a brief sound, and told me that I had program updates waiting for me on my computer
HP Support Assistant (free) download Windows version
You might notice other HP related services as well, please post their names and details here
HP PartSurfer
You might also want to uninstall some of those programs, if you don't use Cyberlink Media Suite or Power2Go or UCam then those programs can be uninstalled