John, I experience this also, at work and at home, both broadband. It just times out, many times when I am replying or being obtuse, and then when you hit back, it is gone (refreshes or something).
for the last month or two, I would say several times a visit, which is about 10 times a day
It is common enough that folks have bitched
and common enough where it is a frustration on my part
ed