See report and screenshot in http://forum.piwik.org/read.php?2,77718
Seems to be a side effect of css3pie. I'll take a look at this...
Ok. It is a problem with the css3pie. Disabling it for the menu fixes the problem.
Didn't find a way to fix it without changing lot of css or changing the html structure. I would suggest to disable it for menu.
Thanks for researching this... should we disable css3pie completely now that Ie8 and ie9 are released?
IE8 doesn't support rounded corners aswell. Only IE 9 does. I would prefer to remove css3pie completely.
Sounds good to remove completely, we have had a few bugs because of the lib, so should be good :)