I had a different 42" 3D Vizio TV (the E3D420VX; the same one JoshuaJSlone has). After about 15 months, the HDMI ports stopped working properly, and the only thing they'd connect to was my laptop. After Googling around, I discovered that this was a common problem with Vizio TVs.
The Vizio support people were no help, and acted as if they'd never encountered anything like this before. When I got my new cable service hooked up, I told the guy who installed my box that I needed a composite cable because the HDMI ports didn't work anymore. His first question: "Oh, is it a Vizio?" Red flag!