Freeze Track (Hangs)

Having trouble with LMMS? Ask about it here.
I've built LMMS 0.4.8 from source, under Debian (lenny).
Machine is an older AMD Athlon 1.33 Ghz 256 MB.
I can playback simple songs live no problem, but I wanted to use it for more complicated projects. I had planned on just "freezing" tracks that I wasn't working on once CPU usage became scarce. To test out this possibility I was using Skiessi-Onion.mmpz. My computer isn't quite powerful enough to render this song live, so I set out to freeze a track or two and see how that might help.
I select freeze on a track
a dialog pops up stating that it is freezing the track
the progress bar quickly goes from 0 to 100 percent
CPU usage hits 100 percent
I decide to give it some time and walk away for a few minutes
I come back and CPU is now 100 percent IOwait
I think it odd, but walk away to give it more time.
I come back and CPU is still bogged with IOwait, terminal is unresponsive.

Anyone know what might be the problem here, or maybe I've come across a bug?
Some more information:
I've been tweaking this system to better suit my needs, those previous results were run under the 2.6.26-2 kernel with vm.swappiness=100. I tried it again after setting vm.swappiness back to 60 with the same results (hung terminal).
I tried again using kernel (real time patch applied). After sitting in the IOwait stage for a while the program exits with the message "Killed".
I'm no expert but I'm assuming that the watchdog detected a dead-lock and killed the process?

What might be of interest here is that I've been able to freeze tracks myself, although I just noticed that the tracks I've been able to freeze have been in the Beat/Bassline editor, whereas in Skiessi-Onion.mmpz the tracks are located in the Song Editor. I'm feeling more like I've encountered a bug (or at least the piano rolls being located in the Song Editor is an unwanted feature?)
'freeze-track' ? I have problems understanding this term. Are you referring to the MUTE indicators? In that case i know of problems if mute/solo/unmute is toggled during replay. These proplem includes cpu spikes, and -most prominent, hanging notes from VSTige instruments (that cant be fixed -project need to reload after a save).
-But i would like an explanation for the term 'freeze-track' if you do not refere to mute/unmute

When you right click on a track, there is an option called "Freeze" (it has a snowflake icon next to it). It renders the audio into a buffer so that it won't drain cpu cycles rendering it live (the buffer is simply mixed into the audio stream). It's like exporting, just not the whole song. This is what I've gathered from the documentation at least.
thanks for the explanation. So it is posible to pre-render individuel note-containers inside a track -Interesting.
I tried with Skiessi-Onion (win xp +0.4.8) and the process stopped. A GUI popup 'hanged' on the screen, but there was no cpu spikes, and i could simply click cancel to get out of the hang. I then copied the notes, and restarted lmms. I pasted the proplem notes in the blanck project and did a new freeze. I now had a fast process and no hang -with the same notes!.
My gues is that the project Skiessi-Onion was made with an early lmms-version that diddent had that freeze option .. something is 'missing' in the project-structure that is needed for the proces to be able to 'run', but test-saving in 0.4.8 did not change anything -so..
Have you had problems freezing note containers in projects created on 0.4.8?

Scratch the above :D
It is the LB302 generators that is the problem. If you remove these 2 instruments it is again posible to freeze note-containers in the track. I have tested this in a default project and found that notes in a 3oc track-container will not freeze if a lb302 is loaded. Remove the lb302 and 'freeze is again posible on the same notes

Alright, good to know what the cause was (and that it wasn't just my machine). I suppose I won't be including that generator in any projects.