Finder Reverts To Old Name When Renaming Files

When I rename a file in Finder, the filename briefly reverts to the previous name before displaying the new, correct name. EG, If I click on a file in Finder named "aaa" and rename it "bbb", the name will briefly (1 to 2 seconds) change back to "aaa" before displaying "bbb". Can any one explain this behavior?

I have a fresh install of Lion on a brand-new 2.2 GHz MacBook Pro. It's been behaving this way since day one, out of the box.