This is far from being a one off problem for esignal. I have seen similar problems on many occasions in ES and AB. I have been told NQ was affected today as well.
The precondition is a high volume market (that seems to be the only thing necessary to cause problems for the esignal system).
The symptoms are:
(1) a relatively short period (no more than a few minutes) of wildly oscillating bad data, where 1 trade can appear to be at a price 10 or more ticks from the last, although the real market is behaving normally.
(2) An extended period (up to an hour or so today) of gradually reducing lag in the esignal data. In the earlier part of this period today, the esignal data was wrong by about 15 ticks in AB (1.5 points). This reduced to being merely a few ticks wrong later on.
esignal has seen this problem occur many times and has not fixed the cause. It is up to customers or potential customers to decide whether this is good enough or not. I for one, am not happy with a $10 refund when it happens