black streaks across my monitor?

Not much information. A link to an image showing the problem could help.
Also, what did you try on your side to resolve the problem?

Check your video driver.
Make sure that the reflesh rate is not set to high.
Ensure that the video cable is securely connected to both the computer and monitor.

Try the monitor with another computer, and another monitor with your computer. This will help tell where the problem reside.

It may be a faulty video card or driver.
It may be a dying monitor.
It may be a faulty video cable having inductance or capacitance isue.

Electro
May 2011