Windows 7 System Restore Setting resets to 100% - never used Avast

Yes, System Restore habitually changes its allotment of my C: drive to 100%. Two or three times a day I have to crunch it back down to minimum.

Not only have I never used Avast on this build, I'm mildly paranoid about cloud applications; I use Steam and OneDrive, but other cloud apps are closed unless I use them directly. I don't allow application updaters or reminders to run at all.

I wonder if anyone else has seen this, perhaps, when running Webroot SecureAnywhere. Otherewise, any ideas are welcome. I'm not sure what else might be causing the problem; it's a pretty clean build only a month or so old. Any ideas?

Try a clean startup - Troubleshoot Application Conflicts by Performing a Clean Startup

Does it happen with another user account?

Check scheduled tasks if you can find something too.

Thanks. I've been troubleshooting this for weeks, so I've done all of the above and more. I should have mentioned that in the OP, come to think of it. I've cleaned out the Startup area of msconfig, I've scoured Task Scheduler, and I've combed the logs for anything that would point to the moment Restore gets reset to try and find what's doing it. And, unfortunately, it happens during login sessions to new, clean accounts.

I think my next step will be to completely uninstall Webroot and see what happens, although I can't find anything about Restore and Webroot caring much about each other.

You have to clean Services tab in msconfig for non-Microsoft services too (check "Hide all Microsoft services").

I went through Services via services.msc.