This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
What's your definition for the Action function? Without that it is not really possible to think of what the problem might be. My guess is that Action has the ability to calculate file sizes in human terms (converting to Kb, Mb etc) and is not handling zero sized files correctly.