Hello, i have my old IBM Thinkpad T40, and when i turn it on(ac), the power light is ok but it will not display the BIOS. and sometimes when i turn it on and everything is ok, when i move my thinkpad the screen will gibberish and hang. what do you think is the problem of my thinkpad.

p.s: sorry for my bad english

Sounds like the GPU has gone bad, you'll need a new motherboard to fix this.

Read the first few pages of this "sticky" thread :
viewtopic.php?f=2&t=33952

Lots of folks have solved the "loose GPU" problem by removing the keyboard and using something thick enough to apply constant pressure to the ATI graphics chip when the keyboard is re-installed. Heat guns, re-balling, and new motherboards are other, more expensive options.

After owning my T40 for 8.5 years, and using it daily for 8-12 hours, I finally had the "loose GPU" problem this weekend and fixed it by adding something thick on top of the ATI chip so that the keyboard now applies very firm pressure to keep the graphics chip seated.