Could somebody please explain the advantages and disadvantages of 'freezing' a track. I read somewhere about freezing a track to conserve resources, which is what I think I need, maybe to prevent the constant lock ups and crashes I get. In Sonars defense I kinda tax it a bit, many times running 10 or so tracks with audio mixed with midi and multiple soft synths and probably too many plugins. (But Sonar has such wonderful toys to play with!) I was thinking that if it's non destructive and would free up resources on some of these large projects freezing may be a concept I need to embrace.
Thanks for any help or advice here!

The resource aspect is #1. The worst program can play a wave file easily, but when FX are active you can potentially recalculate each sample a bazillion times. Freezing simply renders a track as a simple wav file (reversible) so all of the "calculation overhead" goes away. For a VSTi with intensive internal processing is the same deal.

If you need to go back to tweak, simply unfreeze.

 I kinda tax it a bit, many times running 10 or so tracks with audio mixed with midi and multiple soft synths and probably too many plugins

 
With respect, your computer should be able to EAT this amount of "taxing"
 
I'd be looking elsewhere for the source of your lockups & crashes.

Thanks Mettelus, I'll give it a try and see if I can make it work. And Bristol J, I thought so too for a long time but this is all I can come up with.

Just to put things in context, running Sonar 8.5 on my old Win XP 32 box with a Q6700 cpu & 4Gb of RAM, I had a project which had 75 tracks, multiple Fx plugs, upwards of 100 live, unbounced v-vocal clips and many soft synths & imported loops, and it didn't even break into a sweat.

Today's computers can calculate plug-in outputs faster than read freezed tracks from the hard drive but I tend to freeze synth tracks to avoid stuck MIDI notes, lost presets (anything weird can happen when you update plug-ins) etc.
 

I'm running Sonar Professional on a laptop with 3GB of ram with Windows 7 32bit, dual core pentium 2.0 gigahertz, using 3 instances of East West Quantum Leap Symphony Orchestra Silver Edition and it plays a short Symphony piece without a problem but when I freeze the virtual instruments to separate outputs Sonar stops with a dropout and it will barely play the piece! What going here? What is the advantage of freezing the intruments if it won't even play the song after freezing?

That's the kinda thing I'm a bit leery of.
And Jonesey, I really dunno, some of my projects are a little large but probably not as large as yours were. My AMD 8core CPU is outta the box rated at 433, and I'm toting 32GB of RAM. Dunno why I'm getting frequent audio dropouts, and white screen crashes. Did it this morning while trying to add a lead line to a project with only four audio tracks and two MIDI. Each track was sporting at least two fx plugins if I remember correctly. Now one of the commonly used plugs on the piece was Eventides 'Ultrachannel'. Kind of a big plug, dunno if it's the culprit, although the Alchemy player soft synth (Camel Audio) is kinda big too but not huge. It crashed on me three times before I got it to finally take.
Maybe it's the same problem my grandpa used say with my hotrod woes, "probably the nut behind the wheel!"