Erin posted on the forum topic AdminBar broken in Webkit Browsers (Chrome, Safari) in the group How-To and Troubleshooting

By the way, I notice that in the default adminbar.css, the div #wp-admin-bar has three different z-indexes: 99, 999, and 1000 (#wp-admin-bar *). I am no z-index wizard, but that seems odd to me. That 99 seems wrong.