I have a 400mhz Lombard with the DVD decoder option and the original 6GB hard disk.

When I do something processor-intensive for an extended period of time on it the laptop locks up. The fan never appears to turn on to cool off the processor. This occurs with MacOS 9 and X. On MacOS 9 it occurs when paying demanding games. On X it occurs during normal use since X seems to use the machine more thoroughly.

Are there any ideas? Perhaps making sure the metal shield is making contact with the processor....