permalink truncated in ie7

hi.
we are running mu.wordpress for a client.
we’re using permalinks with the format date/postname

on one of the posts, it’s a pretty long postname, and a strange thing happened.
the permalink was truncated when browsed through IE7.

in firefox, browse the home page, hover over the post, and it shows the extremely long url. Click on it and it’s fine.

in ie7, hovering shows nothing as usual, but click on it, and you get page not found. look in the address bar and the url has been truncated.

i tried it in another blog with a really long postname, but didn’t have the problem in ie.

we are using sifr though for the blog with the problem….
but maybe it’s mu.wordpress.

has anyone else had this happen in ie7?