Notebook LCD panel flickers and goes black - reduce brightness to fix
This evening I started having the same problem with my Thinkpad T42p as the one I had a few weeks ago with one of the LCD monitors, which is that has started blacking out the backlight at random, typically a few seconds or minutes after starting up the system. In my case, it was easy to determine that the graphics subsystem was working fine, as I normally have an external monitor connected already, which didn’t have any problems at all. That leaves the LCD panel, backlight, and inverter as likely suspects.
I found some handy resources for diagnosing and repairing notebook display problems:
Here is part of an e-book on diagnosing notebook problems, this section is Notebook LCD Display Monitor Problem
Here is an illustrated step-by-step guide to disassembling an IBM T40/T41/T42/T43 display bezel and replacing the LCD backlight inverter.
For now, the temporary workaround is to simply reduce the screen brightness to 6 bars instead of 7 bars. So far this seems to reduce the stress on the inverter and/or the LCD backlight enough that it doesn’t shut down any more.