What's your screen resolution?
I had a similar problem with strange colours appearing all over the screen and couldn't even get to the login screen. It looked like it was heat affected and I thought the screen was dead, but it wasn't. I wonder if it's the same problem. My problem was that the vga mode was wrong in grub. Try this and see if it works.
1. Boot the computer and when it reaches the grub screen, hit F3 and then esc.
2. Move up or down with the arrows to select which OS you want to boot (when you move with the arrows, the boot options appear across the bottom)
3. In the boot options across the bottom, change the vga=xxx to vga=788
4. Boot into PCLinuxOS.
If it works, you then need to edit your boot menu.lst which can be done by going into PCLinuxOS Control Center and selecting boot, and then setup boot system.
At the first screen click on next, then select your PCLinuxOS install and click modify. Then click on advanced and choose 800x600 in the video mode. Then OK out of everything and then try re-booting to see if it works.