Emac Screen...


I just recently replaced my eMacs hard drive myself. Everything works fine and is the same as before except for one small detail.....Whenever the computer monitor is supposed to go to sleep, the screen goes black except for a rectangular area in the middle of the screen that's a really dark grey and has thin white lines streaking across it left to right. What's going on? Should I worry?
Sounds like the new HD is causing interference with the monitor. I'm not sure if it's something to worry about or not. Someone else will come along and help i'm sure.