Memory controller in the Beige is a whole lot sturdier than the one used in Smurfs. Lombard PowerBooks and original iMacs used the same ropey controller. I have a 256MB stick for my Lombard which is the perfect spec for it, works like a charm under OS 9, worked for a month or so under Panther without issue, having also been happy with Jaguar, then started to crap out all over the place. Weird graphics and kernel panics everywhere. I put it in a box for a year or so, then tried it again. Fine for weeks, then same old story. Finally got another one which is fine. The rejected one also works fine in Pismos as I recall. I think it worked in the Lombard until I restarted it for the first time in Panther (usually I just sleep it). That might have been what caused it to go wrong. Can't think why though.

Stupid MPC106.

I bet your dodgy chip works in the Beige.