Kbase Article of the Week: MacBook: Vertical Lines or Solid Gray, White, or Black Screen After Updating to Mac OS X 10.4.7 →

Apple Support:

After updating to Mac OS X 10.4.7, the MacBook may show a solid grey, white, or black screen or a screen with vertical multi-colored lines.

To resolve the issue temporarily, you may need to reset NVRAM. Once you can use the display again, download and install Mac OS X 10.4.8. You can use the Software Update feature of System Preferences, or download the Update from Apple Software Downloads.

If you have updated to Mac OS X 10.4.8 and the issue still seems to occur, you may need to reset NVRAM on your MacBook again.