I have a HP Compaq presario Notebook with Windows 7 loaded. My monitor screen has suddenly gone haywire. there are horizontal green lines whizzing past when i start the machine and afterwards everything is a pinky purple. Have checked for viruses and cleaned everything. I have noticed that my machine tends to get very hot. Is this a hardware problem?
To be 100% sure it's a hardware problem you can boot from Linux Live CD or connect an external monitor to the notebook and you will see if the display still these horizontal green lines whizzing...
This very much sounds like a hardware problem, either on the graphics chip, the display itself or the connection between the two.
The fact that the effect changes would at first glance rule out the display as that would more likely be a single permanent effect.
If this were a desktop system the "pinky purple" hue might indicate a loose connection between the graphics output and the display so that the screen isn't getting one channel of colour. If you can open the laptop up, checking the connections between the graphics chip and the display would be the first thing to check.
On balance, however, I'd say that it was the graphics chip that was the cause of the problem.