System maintenance restricted on my Gateway PC?

Whenever I try to do any system maintenance on my Gateway PC, it blocks me as "restricted". It's my PC!

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My path: Control Panel > All Control Panel Items > Troubleshooting >

Run Maintenance tasks > Next

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" An unexpected error has occurred. The troubleshooting wizard can't continue."

Open the link to Details, and it says

"Package ID: Maintenance Diagnostic

Path: C\Windows\Diagnostics\Scheduled\Maintenance

Error code: 0x80070002

Source: Engine

User: Margaret-PC\Margaret

Context: Restricted "

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Until recently, I had PC Doctor, that enabled me to do these through it. But Norton Security has replaced it, and doesn't have these facilities. I think it takes for granted that you can do it all from Control Panel.

Does anyone know how to get access back for this purpose?

Thanks in advance.