Every antivirus software be it free or paid has false positive issues. Comodo has the highest false positive rates. As you can see by the chart in AV Comparatives Avast has a much lower false positive rate then several other programs. Microsoft Works is an extremely old and out dated program. It is no longer support by Microsoft therefore leaving you prone to vulnerabilities. If you need a free Word program then download LibreOffice Free. Microsoft ditched Works about 8 years ago or so. So if they do not use it no longer should you. What else do you use in Works that you may need? I bet I can find free and up to date software for anything that Works can do. Thanks.

http://chart.av-comparatives.org/chart1.php

Certainly a false positive on Microsoft Works will NOT make your pc unbootable. As in matter of fact 2 years ago or so Symantec had a HUGE false positive which did just that. No one could use there pc’s at all. Had to go into Safe Mode which sometimes did not work. I have never seen Avast have a false positive which can prevent a pc from not booting. Simply adding it to the global exclusions will fix your issue permanently.