I have a Norwood LX961 monitor with a DVI and DSub input and would like to connect two computers to the monitor using DVI for one and DSub for the other.
I have an Apple G4 hooked to the DVI and a PC hooked to the DSub and each works well independently but if I try to have both computers on at the same time, the DSub input overrides the DVI input.
I use the source switch on the monitor to switch back to DVI but after a second, the DSub input overrides the switch again.
Any suggestions appreciated.

Why don't you use a KVM switch? You use 2 computers with one monitor, mouse, and keyboard
http://www.newegg.com/Product/Product.aspx...N82E16817394013
You can also get them to switch between speakers and USB and for 2 to 4 comoputers. You can do more, but you're getting uo there in price

Thanks for the link.
I'm not sure that would accomplish my goals AND in conversation with Belkin, their switch only works with 2 DVI inputs when trying to combine Mac and PC on one monitor. Unfortunately my older PC only has VGA.
Anyone else?

You could use a VGA to DVI-I adapter. You will need to have the VGA as Male and the DVI-I as male so you can plug one end into the computer and a cable into the adapter. The adapter needs to be DVI-I so it will have the 4 analog pins which will transmit the analog signal from the VGA port. I am not sure if this will be compatible with the Belkin KVM switch. You could use a DVI-I to VGA adapter to convert your G4 to analog although you would loose the digital quality but gain the use of both computers on one monitor.