I just learned a valuable troubleshooting lesson. It cost me a monitor I bought needlessly. I had a problem with one of my pi's, I thought. The vga display had either no red, or all red, switching randomly between the two on one of my pi's. The other one was my web server so I just disconnected the HMDI connector and plugged it into the pi with the problem. The color was fine so I bought a new monitor thinking it was the problem. NOT SO! Since the problem persisted I disconnected the HMDI>VGA adapter from one setup and connected to the other. The problem turned out to be one of the HMDI>VGA adapters. Both were the white ones purchased from element14. So if you have one of these adapters and experience this problem, be forewarned and save yourself some money.