PB G3 Lombard crashes in MacOS X


I have a Lombard G3 PowerBook 400 mhz with 30 gig hard drive, partitioned with OS 9.2.2 on one side, OS X 10.2 on the other.
PC card for one firewire port.

It crashes in OS X when it gets a little too taxed by programs like Photoshop or is downloading software updates. That isn't good cause I have to do a total reinstall then.

I ran Memtest, a unix based ram tester and discovered the original 64 mb was bad and took it out. That left the machine less prone to crash on Photoshop start-up but that was about it.

The remaining 256 mb runs with flying colors using Memtest but the crashes continue. All I have to do is run Radial blur in Photoshop and it is toast.

I was told by an authorized Mac tech guy that some other component is bad on the laptop and needs to be replaced. In his judgment, it is running too hot so something is wrong. He said it is a hit or miss to replace components. The Unix base in Mac OS X does not like any components that are not running perfectly.

Is there a way to test the other components? Any other options would be helpful. Thanks in advance!!

Someone in another forum recommended dusting the machine on the inside. Anyone got a pdf of the powerbook manual?