CCleaner won't run & Admin privileges are gone

[conradauthor]

Greetings,

Security may be the wrong place for this, but it does relate to keeping my computer safe.

My laptop runs Win 10, 64 bit. I use Malwarebytes antivirus. I use CCleaner Pro.

In the last 3 weeks, a problem has developed. The CCleaner icon disappears from the task bar and I am unable to run the program. This includes using Windows Explorer to go directly to the .exe file.

I tried downloading the CCleaner file and reinstalling it. This is when I discovered I have also lost Admin privileges on my Admin account. I used Safe Mode to delete the .exe file then reinstalled CCleaner. It worked for less than 48 hours before CCleaner stop working again. I have gone through this process twice.

Today, CCleaner does not even install. And my system still tells me I have no Admin privileges.

To be clear, I have Admin privileges to install software, and Windows says my account is an Admin account. But I have no Admin privileges when I want to rename any folder on C:, or delete a file. I can make changes to user created files, but not computer/software created files. The loss of Admin privileges is quite specific.

A Malwarebytes scan (pro version) has found nothing amiss.

There have been no software installations to cause this. There have been no hardware additions either.

I very much need advice to get this resolved.

Thank you.

Edited May 6, 2020 by conradauthor
adding clarifying information

[Nergal]

Moved to ccleaner help board

[nukecad]

Losing Admin privileges is something that happens to Windows user accounts now and again, (if you google it you'll find plenty of hits).

In your case it sounds as if your User Admin account has lost some ownerership permissions.

The first thing that I would check if if your Windows security has anything set that could be causing this.
(I recall that at one time their early attempt at an anti-ransom meansure would not let you rename or delete things unless you were using an MS app to do it).

Other than that you may need to reset your User Admin account(s).
You may have to enable the hidden Elevated Administrator to do that. The third link in the Microsoft article below tells you how to do that.

There are instructions here on how to fix it, up to and including the drastic measure of having to reinstall Windows:
https://answers.microsoft.com/en-us/windows/forum/all/lost-administrative-privileges-win-10-pro/f91f5a48-e7c4-4039-bd82-c9d7c6918972

As you are already a Malwarebytes user then if you are still having problems you might also want to ask their experts to check over your machine for you, just to make sure there is nothing lurking deep.
It's a service that they offer for free.
https://forums.malwarebytes.com/topic/9573-im-infected-what-do-i-do-now/