Rupert Goodwins wrote:

Now. Is it purely coincidence that the machine spasmed immediately
after getting an Oyster meal, or is there a bug there? I've never had
this problem before, and I've never seen anyone use an Oyster card
before. Just one of those things -- OR SOMETHING MORE?

Dunno, but I get the opposite problem regularly. Perhaps too quickly
after a paper ticket has gone through (but it accepts it), I swipe
Oyster, it goes green, the gates stay open after the person in front,
but as I get to them, they close on me, and my Oyster will then no
longer work in ANY of the gates at that station.

Happens regularly at Blackhorse Road and Walthamstow Central, though
have had it less often at South Kensington (this is probably not
relevant, these just happen to be the stations I use all the time).

After being let through by an SA, I never have any problems exiting at
the end of the journey. Oh yeah, and these are always entry problems,
never exit problems.

Dave