I don't know if anyone else has noticed this problem, but SharpReader seems to prevent my XP Pro machine from shutting down. I typically leave SharpReader running all day, minimized to the systray. If I don't manually shut it down before shutting down my system, the OS seems to get stuck when it gets to SharpReader. If I right-click on the SharpReader icon and choose Exit, I can then shutdown my system just fine.