The first point I think is to confirm that there is no doubt that there is a serious problem here: some authorities denied it initially - I have to admit I was dubious myself when I first saw the claims because it had seemed like such a fine vintage. If you doubt it, consider the fact that the Wine Society (admirably, in my view) proactively contacted customers who had bought certain wines in this vintage and offered refunds or exchanges. I want to address two points: what is known about the source of the problem and is it true, as some have suggested that 96 is just the clearest case of a general problem with recent vintages.
So what happened in 96 and why did it not affect other wines (the reds from the same vintage, for example)? One theory is that because of peculiarities of the vintage the 96's had to be rushed out of the cellars before the sulphur was fully absorbed. (Sulphur is added in stages - the wine absorbs some and one stops once that process is over and there is sufficient remaining to protect the wine.) This, combined with a modern (and wholly admirable) tendency to use as little of the chemical as possible caught a lot of growers out. As an idea it seems plausible and connected with another idea which is that the vintage produced healthy-looking grapes which in fact had concealed rot - growers imagined sulphur was hardly necessary. Another notion going the rounds is that the vintage was never much good anyway and that this is just premature ageing. I don't believe this - the wines seem to be decaying rather maturing in the usual way and I think this theory is down to people who don't like the acidity of the vintage (a feature that is much admired by the more classically-minded European palate) jumping on the band-wagon.
And is the 96 disease just the most prominent example of a wider malaise? While at the extremes one can find people giving accounts of dodgy wines as far back as 1990, the more serious-seeming accounts date the problem from around the 1995 vintage. I remain open-minded on this. I certainly think there is a quality problem: leaving aside oxidation I can only think of one or two producers that I really trust in the classic areas of the Cote de Beaune, compared to dozens of producers of red Burgundy. This may be down to complacency or excessive yields - and a desire to make early-maturing, softer wines by lees-stirring (among other techniques) may be contributing to short-lived wines too. But I haven't myself tasted many non-96's that have gone in the way of the worst examples of that vintage and I remain a bit sceptical of claims that 1998 is turning out to be similar.
If there is a problem beyond lackadaisical producers, the most likely candidate seems to me to be cork-washing with peroxide solution prior to bottling, a technique that I believe became common in the mid-90's and given that this chemical is a powerful oxidant it could easily lead to advanced wines - if people used this carelessly in 96, not rinsing it off the corks properly it could even be a major contributor to the particular problems of that vintage. One increasingly hears people noting "blue-tinged corks" which are apparently a result of this process. I do think a lot of what one hears on the subject is ill-considered, partly because the very features of the problem - the way it seems limited to white wines from this particular region - suggests that the cause is probably a combination of things: low sulphur might be a cause in the sense that more sulphur might have averted the 96 debacle, but given that very low sulphur wines are produced all over the world it also can't be the whole story - it's the same with every other "cause" that one thinks of.
For now, my advice is that purchasing any 96 white Burgundy (including Chablis, but not as far as I've heard the Macon, etc) is a big gamble. And
I am being extremely selective with all the other vintages back to and including 95. A good start to winning my confidence back would be for the estates to
admit there is (or at least has been) a serious problem.