My dad just bought a 24" iMac for use with his design company as his main machine. While installing his new software, I noticed this band on the display. It was visible at startup, but more or less disappeared after. I started to notice it as I was applying a firmware update. Has anyone seen this before and was able to find a solution? I would really, really like to avoid taking it in for service, so I'm hoping it's a software problem that can be resolved easily.