New to Vista - Can't set network configuration

Hi,

I just installed Vista CTP (Feb 2006) on a machine I just finished
building (MSI K8NGM2-FID) with an Athlon 64 3000+.

The installation seems to have gone ok, but I need to set my network
adapter to 10Mbps Full Duplex instead of Auto-Negotiate. I can get to
the Network -> Configuration -> Advanced settings, but whenever I try to
select media type and the dropdown box for 10Mbps Full Duplex, etc., the
whole network applet vanishes before I can click on OK.

Anyone have an idea of what I might be doing wrong, or how I can do
this?

Thanks,
Jim