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Adding to what FWF said, add it to the exclusions until corrected.

If it is indeed a false positive, add it to the exclusions lists (Standard Shield, Customize, Advanced, Add and Program Settings, Exclusions) and Restore it to its original location, periodically check it (scan it in the chest), there should still be a copy in the chest even though you restored it to the original location. When it is no longer detected then you can also remove it from the Standard Shield and Program Settings, exclusions.

Also see False Positives, how to report it to avast! and what to do to exclude them until the problem is corrected.