This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Intrigued, I tried this, and it worked for me. I created a new Maven-based project, created two classes with printlns in main(), and they both ran without issue by right-clicking on the class and selecting Run As > Java Application. There must be something else going on, or different about your project that you did not mention.