When I go to http://su.dk/ and click on the first of the four purple buttons ("Log på med" -> "Digital signatur"), Firefox 4 loads the page, and Java shows its normal security warning dialog, which it usually does for signed Java applets. However Firefox is completely frozen, and I cannot click anywhere in Firefox or the Java security warning. After some time (30 seconds or so) the Java security warning closes, and the Plugin crahed infobar shows instead. Now the Firfox window responds, but I cannot see any text selection or the text cursor until Firefox is restarted. The crash reports generated are for example http://crash-stats.mozilla.com/report/index/dd902e52-253a-4093-96e1-467072100823 and http://crash-stats.mozilla.com/report/index/07cd8b91-d960-437d-bba9-6d2a72100823 but this happens consistently.