It's understanding the difference between a 'resident' & an 'on demand' anti virus programme. You should have only one 'resident' but you can have as many 'on demand' as you like.
Unfortunately these days many AV programs configure themselves as a constantly running background checking facility as default. Yes, they then can be configured not to do this and only run on user command but again many come with (unwanted) embedded features that still run in the background.
I guess for the technophobes the dire warnings about switching off certain features puts them off from doing so.
And, then there is the crap they leave behind when they are uninstalled. I had one of the well known virus checkers leave behind a update checker. A month after uninstalling up pops a window telling me that there is a new version with the option to "download and install. This then became a constant nag, appearing every day. A web search was required to find this update checker file obscure name in order to delete it.
I now regard many of the popular AV suite of programs to be viruses themselves. Almost gone are the days of the simple virus checker without all the unnecessary bells and whistles.
These days I just let the inbuilt MS Windows checker run with it's daily updates and use the free version of malwarebytes to check my downloads where I'm not sure of the source. Malwarebytes defaults to turning off all the "added" features if you don't pay for it after the trail period.
Take the machine back with system restore, and if the problem persists, then AVG might be the culprit. I have to say, I'm still using the built in anti virus and a weekly scan with the free version of superantispyware. Its not as invasive as AVG or Avast are. I had nothing but tryouble with both of them, and now Windows 7 is so far out of support, many anti virus programs are using the compiler from Windows 10 era and this tries to use dll libraries not in Windows 7, with unpredictable outcomes. Brian
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