Steve Bucci, recently posted another great video he put together that shows you how to troubleshoot and correct some common configuration mistakes by guiding you through the areas to double-check in a typical App-V deployment.  Whether you're new to Microsoft Application Virtualization or a seasoned veteran, you'll definitely want to spend the 10 minutes to check out this short video: 

For more information on troubleshooting some common App-V issues see this post by Microsoft App-V Support Escalation Engineer Steve Thomas.