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I do get errors like this in the LuxRender Log window:

[2010-09-02 14:01:43 Error: 14] Static loading of color texture 'default' failed.
[2010-09-02 14:01:43 Error: 41] Couldn't find color texture named 'Color_Round' [2010-09-02 14:01:43 Error: 41] Couldn't find float texture named 'Color_Mul_74'

this is "normal". These are textures that couldn't be exported at the moment (texture here does not mean: "image", but a shader-setup).

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and the last thing it says before crashing is:

[2010-09-02 14:03:21 Warning: 0] Parameter 'from' not used  

[2010-09-02 14:03:21 Warning: 0] Parameter 'to' not used

This parameters are from light. with certain lighttypes "from" and "to" is not required. So the log message it's just a hint.

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Then I get a popup window saying:
 Runtime Error!

Program: C:Program Files LuxRenderluxrender.exe

This application has requested the Runtime to terminate it in an unusual way. Please Contact the application's support team for more information. 

I have tried running the sample that comes with Luxrender and that goes through fine without any trouble. So I don't know what I am doing wrong that is causing so much trouble. I have been in contact with a couple of the people working on  this project and the LuxRender Devs, and both have told me that it is a problem with relative paths vs constant paths, but that doesn't make sense since I have taken out all of the relative paths. And it is not just one scene that I have tried, it's all the of the scenes I have made and tried to move over to LuxRender.
 

Do you use IBL for your scenes? If yes, check the images used. You problably  have to convert them to OFX-format. I also had some crashes for this reason. Some seems to work in Lux, other may need conversion.
For the first test I would check a scene and turn off all IBL light. Or, just to be sure, switch all light off but one. Make this a pointlight, move it high above your scene, raise the size of the light to 500% and intensity to 100%. Raising the size of a pointlight makes no sense in Poser; but the converter makes it an arealight and the size of the pointlight is the size of the resulting "light-source" in Lux. If this exports and renders fine, just the light/IBL is the reason for your crashes.

Another possiblility is you have the wrong Lux Version for your processor type. Or try one of the weekly builds. The latest seems to have a few fixes.

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