i'll try, but end users probably use ie5.0. :(
do u mean that i should modify the <META> element? in fact, the local files r generated by myself, and i can replace the html text of the <meta> tag. but must i modify the document? is this the best way? can ie be set into a 'static' mode?
ps: i tried to increase the time interval to nonzero, and then the browser just alert once. it looks like a bug.