Lavasoft recently released a new build of Ad-Aware program by adding new features (email scanner, for example). Today, Lavasoft has issued a fix and wrote in a blog post:
Following this week’s release of version 8.2 of Ad-Aware, Lavasoft became aware of an issue with scanning that affected a limited number of our Ad-Aware users. This has only affected users of Windows XP (Home and Professional).
We sincerely apologize for any inconvenience or concern this may have caused. Lavasoft’s developers prioritized this issue in order to promptly resolve it, and a software update to fix the issue has now been released. In order to resolve the issue, please update Ad-Aware by clicking "Web Update."