I get two error messages whenever I attempt to render HD content. I can render with no issues with the PI interface in lower resolution. When pillusionrender starts to render, I get the error "Could not find an acceptable pixel format", then "Can't create OpenGL context" I am trying to render a series of still images.
Open pIRender and click the "options" button and turn off hardware acceleration. That's the short-term fix.
The long-term solution would be to get the latest video drivers for your card.
There's a chance that your hardware/drivers don't support the features that pIRender is trying to use, so you may be stuck with software rendering.
Have you already maximized your pIllusion window (so the application fills the entire desktop) before rendering? If your desktop resolution is high enough, this will enable you to render right in pIllusion and bypass pIRender.