With the caustic i'm not sure - never used caustic in my images yet - but there is always the option to add a fake with postwork ...

A lot of times you can ease the strain on Vue, if you first save your Poser figures in Vue one after each other as Vue objects and replace the Vue objects with the relating Poser figures ...

You could calculate your scene more than ones and calculate each image just with certain Poser objects (as long as they aren't overlap with body parts or shadows ...) - or at least split the number of objects in each render - then take those few renders and use area copy or copy brushes in good paint programs and combine all elements into one image - this way you can stop Vue from crashing ... sure this is extra work, but for certain parts in an image it works

Okay - this doesn't fix the problem - but just as a workaround:

Maybe you could download and try this in the PLE  Vue 6 Infinite version ?!
Where you trying to load the P7 props into a already bigger scene or are you trying to load the props into a new and empty scene ?!
If it would work in a fresh empty scene, you could save the props as Vue objects and then load them into your scene...
Or you could export your not working props already in P7 as wave-objects and use those in Vue ...
Or maybe some setting in the P7 preferences - misc. settings have to be activated/deactived to get better results ...

Well, only until working updates would be released ...

Have you updated to the newest version of Vue 6.10 (version 291551) ?
Maybe that would help already.

Or have you updated your graphic drivers since last time ?
f so, you would have to change some OpenGL settings in your graphics card panel ...

Or did you try to call up the Vue options and change the 3D view OpenGL from hardware to software acceleration and check, if it's still crashing after the change ?
Again, if that would work better, some changes in your special OpenGL settings in your graphics card panel could do the job ...

Well, your error display doesn't give us any clues - have you clicked on "click here" to read more about the details of this error report ?

Maybe you could download the free PLE version of Vue 6 Infinite - install it and check, if the problem is occurring there ... and if so, i really would count the OpenGL settings as one of the highest error candidates ...

Attached Link: http://img107.imageshack.us/img107/7808/imageonsurfaceofsphere1nj8.jpg

I've made an example screenshot  - attached to this reply ...

Maybe it can be of help ...

I'm using a 19" Samsung Syncmaster 931BF - contrast 2000:1 - 2ms reaction time - 5:4 format. Before that i've used a 19" CRT , which was a very good display - but after a while the light arched screen with faded colors at 1280x1024 Res setting bothered me and i've noticed my "older" getting eyes to strain more after a longer time ... 
After checking LCD displays in stores and reading online tests on LCD monitors i've found the above mentioned LCD screen as one of the best in price and performance. And i have to say, that i'm very pleased using it for over a half year now and don't miss the CRT "big size box" monitor - except that i have to keep the 1280x1024 Res setting everywhere, because that's the only resolution, where it will look crisp and clear - that's the problem with LCDs, it only works with the 1:1 LCD dot setting perfect.
And ... only straight looking towards the screen shows you the right colors - so you have to make sure your visual line of sight is perfect perpendicular towards the screens surface - or you won't use the right colors in your graphic images ...

Nice i can thank you for all your great free usable castle models in this posting of yours !
I for sure will grab the Karhen castle and try to come up with a nice scene for it in the near future !
(Your castles used in certain images in my Kilanor and GSGALAXY galleries)

Most of times creating a seascape scene, i'm not using the ground or a flat plane and add a regular liquid material, instead i create a procedural terrain (in the advanced function editor i choose the "ocean" function), adjust the wave length and height and then i create a mixed material - one a liquid material and the other a foam material.
That way i can control quite detailed, where i want the foam to appear - which should be mostly on the higher parts of the ocean surface, like the peaks of the waves should have most of the foamy material. To get this result i use the 'influence of environment' tab to set up the appearance in height, slope, direction sliders and using the 'smooth blending strip' in the 'material to mix' tab to make some more fine adjustments.
You could use a second copy of this ocean terrain and change some settings there, to mix it up with the first ocean terrain by changing the height, position, rotation a little bit ...
That's tuning work then ...
But that's just another way, to get some result working with water surfaces ...