Hi Eoin, it's great to see you around here again. It's unfortunate that your first experience back has been a negative one, but I hope you'll give it some time and do a bit more experimentation. By and large the TG2 final is pretty stable. The main issue you run into, which we don't yet have good error handling for, is memory - as Mohawk mentioned. If you do something that happens to use too much memory, it will usually just crash rather than gracefully let you know. We do intend to improve that behavior in the future.
In the meantime there are a few things you can do to help. First, you can turn on preallocate subdivision cache in the Renderer settings Advanced tab. This will help detect memory issues early by attempting to allocate the majority of needed memory at the beginning of the render, rather than increasing memory use over the render period.
Second, be judicious about your use of detail settings. Because of the many different detail settings and the level of control offered in TG2 vs. TG 0.9 it's a lot more risky to just crank every detail setting, especially with complex scenes. You've got a detail of 0.9 here which, while not terribly excessive, may simply be unnecessary (0.7 often provides a great level of detail with much lower render time), 3 *Very* high detail populations (did you test with lower detail to see if you needed Very High?), and a 3D cloud layer with nearly 300 samples, equating to a relative "Quality" value of 3 for that cloud layer. Now all of those are potentially reasonable settings *if you need them*, but it's important to realize that you often simply don't need "max quality", and it's best to experiment with crop regions and lower detail renders to find the best balance of detail, quality, and render time.
Third, keep an eye on your memory use. You have 3GB of memory, but that doesn't mean TG2 can use that much. TG2 is a 32 bit application running in a 32 bit operating system, so unless you have special tweaks configured, it can only ever use a maximum of 2GB. And if you have other apps running, it can be even less, especially when it needs to allocate a large block of contiguous memory (if available memory is sufficient but fragmented, the allocation can still fail). One thing you can do which may help is enable the so-called "/3gb switch", which is a configuration trick to allow applications that are properly setup to use *up to* 3GB of RAM themselves. Of course you only have 3GB total so this could be problematic, but it may be worth experimentation.
I hope that provides some useful information, and I hope you keep trying long enough to see how far we've come since TG 0.9.
Edit: forgot to mention a few other things you can do. You can reduce the size of the cache to conserve memory. This *may* slow down rendering, but it's a useful option to consider. There is a lower limit, I believe 200MB, but vs. the default 400MB you're saving half the memory, so it may be useful. The other option to consider is using less render threads. Your quad core will use 4 by default, but each additional render thread uses more memory. Of course it's not ideal to cut the number of render threads down as you lose performance, but again it may be a useful troubleshooting option or last resort. Hopefully the other ideas above help more.
- Oshyan