After a period of time, maybe 12 hours or 24 hours (can't remember now), everything came right.
I have not made any changes since so I don't know if it is a problem that will recur.
I use the Web Developer extension on Firefox. It has an option to disable cache. I had checked this, and when this didn't fix the problem, I use Firefox to clear the cache. I think that when that is checked, that clearing the cache doesn't work.
However that does not explain the fact that Safari was similarly unable to get the new file.
I think it is a chacing problem. I think it is related to the time stamp on the file: if the time stamp does not say the file is newer than the present time, then it wont collect it.
I use a server that has a time that is in the past in relation to my computer so this should never be an issue, but there is a whole bunch of sfotware determining how to resolve time zone variations, and there could be a bug in that.
The simpleviwere owener has not responde to this, so I don't know if there is something in the flash file that affects time zones.
SO I would be itnerested to know if your problem disapperas after a time period, and maybe you could keep a better eye on teh time taht I did, to determine how long that time gap might be. And when next I work on my galleries, I will do the same.
Best of luck