HELP!! White line across the screen!

Everything was fine, I just let my pb go into screensaver than it went to the display off. A little later I came back and moved the mouse and the password box came up. Only this time at the bottom of the screen about 1 and a half inches up (a tad over where the fully extended dock ends) there was a white line that runs across the entire screen. Oh and strange thing I took a screen grab and the white line doesn't appear on that grab image. But like the line blocks text and anything in the way of it on the screen!! I am really angry now! please let me know what this could be and I am going to call tech support now hopefully get this straightened out. But how could something like this happen all of the sudden. The computer is barely a month old.

Restarted it since?

yeah didnt help. I called tech support and tried lots of stuff to no avail. He said try rebooting from the disk to see if its a hardware/software problem. Then if not then need to send it in. This is a pain!!

What caused the white line?

I am having this same issue with an older iMac. I was wondering what the techs said was the problem?