Great day in the mornin'!
Between the two threads, over 125 posts from this (!)...
This just ain't that hard, folks. The OP asks an innocent question... and the next thing you know his instructor, his class, his background and everything but his parentage is questioned! There's just no reason for it. His allusion to Nitrox and "Any ideas why...?" is (1) saying "I can't think of any reason based on my training" (good training! there is no reason) and (2) asking "is there something I missed?" and the answer is simply "nope." No need to extrapolate any lack of training or knowledge there... just answer the question!
The answer, Ben, is "no, there's no reason Nitrox could have anything to do with the problem."
Now we can go on to discuss valves, regulators, filters and anxiety, and perhaps a couple of really obscure possibilities for the problem. The 120 posts on everything *but* the problem are mainly blamestorming of the worst kind... blamestorming without a shred of basis.
Rick (standing by for heavy rolls
)