This file is a part of ACT! application, published by Best Software company. However, when you do not have ACT! installed on your computer and do not use other business software, but have actalert.exe running in background, then your computer most probably is infected with a virus or a spyware. Use antivirus and spyware removal tools to check your system. Do not to remove legitimate actalert.exe, even if you had a virus: malwares do not replace an original file, but run own files with the same name.
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