Hi lancaster1926,
I would suggest you do a program update to the latest version of Avast. When you do so, you'll get the updated version of GrimeFighter, which is now called Cleanup. It's improved in many ways and I think should solve your problem.
You can do the program update by opening the Avast program and going to Settings, then Update, then under the Program section click "update"
Please give it a try and post back if it worked or not.
Many thanks,
Davidek