Unfortunely it depends on what cubase version you are using. I use a rather old version- more specifically Cubase VST/32 version 5.1 R1
My version of cubase has no such option for track freezing. Although I have heard of this feature being in the newer versions of cubase SX. This may be the best way to go if you are using SX otherwise my way maybe your only option.
This is how you export a file in Cubase VST/32
Using the pull down menu click:
-->File>>EXport>>Audio Tracks...
or
by using VST Master Mixer Panel click:
-->Panels>>VST Master Mixer
then click the "EXPORT AUDIO" audio button on the panel
Basically this is where you would create your mixdown down as well assumming you wanted to use all you tracks or just the one track.
Also make sure you check that the track got imported back into your song. Otherwise you'll have to imported audio file back in manually. I think there an option you can click, but I can't think of it off the top of my head at this very moment.
I'm assumming that you could probably find it in preference menu if you look for it.
freezing cool - I like it.
Oh btw these instruction were meant for anyone using Cubase VST/32.
Although I don't use SX I have seen the intereface enough times to know the vst/32 and SX look totally different.
Actually SX looks more like Nuendo to me which I tried and never really like it enough to make the change over to it or SX.