When making a tasklist that numbers over about 35 items, Internet Explorer will basically say "page not found" if you try to move tasks around in the task list or create a new task.
The link Confluence is trying to direct IE to is http://abhoth.netdevil.com/login.action;jsessionid=F5BCE97541732C5EC8807E85BD1442EE?os_destination=%2Fplugins%2Fdynamictasklist%2FreorderTasks.action%3FtaskNames%3D%252CLobster%252CRock%252CHelp%252CMud%252CTask%252CControl%252CSyntax%252CRobot%252CHarry%252CPurple%252CDeli%252CTurkey%252CJuice%252CHotdog%252CYellow%252CBasket%252CFruit%252CCase%252CShell%252CTrigger%252CBomb%252CFTP%252CDrill%252CConquer%252CLiquor%252CTrouble%252CJeremy%252CNasty%252CYell%252CDribble%252CTaxes%252CTelling%252CJokes%252COrganic%252CHellian%26entityId%3D3703034%26listName%3DRockLobster

The task editing features however, still work within Firefox - this seems to be a problem isolated to Internet Explorer.