I have Rails project setup that runs Cucumber features via Selenium. I have a vanilla Ubuntu 9.04 AMI setup with all of the requirements to execute the tests via the rake runner in the cloud via EC2. The AMI is configured to run the tests on a 'headless' browser setup via Xvfb. The configuration works and runs the features fine when I invoke the rake task on the instance. However, when I run the tests from TC, Selenium fails when trying to open the browser (firefox). Any suggestions?