You could also try the free GoPro Cineform Studio, convert the files to Cineform and try importing into Lightworks again. This would put the material into an intermediate codec making editing easier and might let you continue with the free version.
If the GoPro HD2 new firmware ever comes out, I have a feeling this will become the standard GoPro workflow since they will need to do color correction on the files before any other task, and this correction may require GoPro Cineform Studio (details are still slightly lacking on this firmware).
@SMPse & ScottHill:
Thank you very much for testing
Thank you for the backgroundinformation. Nevertheless nobody asked for flip video cameras on the web. I know that has nothing especially to do with the codec. Anyway, now these"keywords" are set.
I think I'll try GP CS but nevertheless I'm also willing to pay for LWKs. Let's see. Maybe I trink one or two cocktails less, next weekend.
Keep you posted, but for now the topic is "solved".