Plugin in testing - countdown

Plugin in testing - countdown


I have written a plugin that counts down towards a date (for instance
an important event, birthday, new years day etc):
http://www.texotela.co.uk/code/jquery/countdown/
During testing though, I found the timing somehow seemed a bit off in
Firefox (strangeley enough, IE seems to behave as intended). Two of
the examples run the counter every second, but for some reason the
time in seconds does not decrement each time by one (sometimes two or
even three). If I only have one countdown (that runs every second) on
the page, I don't see this happen though.
All I can think of is changing it to check the time every half second
or so, rather than every second.