I would strongly urge you to upgrade from 5.1.889 to 6.0.1125. There were too many issues and/or glitches with 5.1.889. You will find 6.0.1125 is more stable and stronger.
- download 6.0.1125 http://filehippo.com/download_avast_antivirus/download/1f05c500f7b63ab5059bc878c34ae345/
- use the uninstaller (follow the directions)http://www.avast.com/uninstall-utility
- use CCleaner http://filehippo.com/download_ccleaner/download/4fb7421e246bf93c9debbe95dce27ce1/
- install 6.0.1125
- relax and let avast do its thing.
