My mac is slow, freezing and has horizontal lines. How do I fix this?

Question

Hi, my mac is freezing, slowing down and horizontal lines appear.  How do I fix this?

Answer 1

Run the Hardware Test in Extended mode.
Using Apple Hardware Test
Using Apple Hardware Test
You can use Apple Hardware Test to help determine if there is a problem with your computer’s hardware.
To use Apple Hardware Test:
Disconnect all external devices from your computer except the keyboard and mouse. If you have an Ethernet cable connected, disconnect it.
Insert the “Additional Software & Apple Hardware Test” disc that came with your computer.
Restart your computer and hold down the “C” key as it starts up. A list of available startup volumes appears. Click Apple Hardware Test and click the right arrow.
When the Apple Hardware Test main screen appears after about 45 seconds, follow the onscreen instructions.
If Apple Hardware Test detects a problem, it displays an error code. Make a note of the error code before pursuing support options. If Apple Hardware Test does not detect a hardware failure, the problem may be software related.
For more information about Apple Hardware Test, see the Apple Hardware Test Read Me file on the “Additional Software & Apple Hardware Test” disc.