I would love to help you, but I'm not sure that I can with the information we have. One thing to try would be to open Firefox, go to Tools > Options, then click on the Content Tab. Make sure that block pop-up windows, load images automatically, enable javascript and enable java are all selected. Under the exceptions button for load images automatically, make sure that the Vonage site isn't listed there.
If that doesn't work, you might try uninstalling and reinstalling Firefox. Beyond that, I'm sorry, but I don't know what the solution would be.
Sr. Network Engineer
A+, MCP, MCSE, 15 years of experience