I have this same blue fringing problem with my PDW 700. I see the hard blue lines like a blue neon sharpie, especially near the edges of frame on the wide end of the lens, this is as well as the standard purple and green aberrations one might normally expect.
I was originally using this camera with Canon SD lenses (J17 and J11) and I blamed the lenses. I am now using HD lenses HJ17 and HJ 14 (alac) and the problem it is no better. My thoughts are that is probably the block more than the lens but it is hard to be sure. As Alastair said, each manufacturer will blame the other. When I first bought the camera I took it back thinking that I had a duff camera but was told there is nothing that can be done to help other than turn off matrix and colour sat which I am reluctant to do. Basically my supplier said it was probably the lenses ( even though he said he has also seen this problem with zeiss primes). He then went on to say that my camera does not exhibit is as badly as some 700's / 800's /500's he had seen.
My guess is that the blocks are made to meet a certain spec for aberrations and you may be lucky and get a good one or you may get an average to bad one. When paying £25K for a camera we should expect them all to be perfect.
What I don't understand is why was this not an issue with tape based HDcams - or maybe it was and we have only just noticed it because we can now playback our rushes at home. Also I have been scanning the forums about this and there is surprisingly little written about it considering these are such popular cameras for broadcast acquisition.
If there is a solution I would love to know as every time I shoot against the light I worry that the 'blue meanies'

Chris