Pull down menus do not appear in IE6 when the username is longer than 26 characters

In 3.1-RC2, the "User", "Tools" and "Add" pull-down menus do not appear on hover when using IE6. The "Browse" menu does appear as expected.

Does not reproduce in RC1, or in IE7/8/FireFox in RC2.

Edit: This is reproducible when the user's Full Name contains special characters such as [,],<,>