Gmail Bug: More Actions menu

Stumbled across a new bug in Gmail.

The drop-down menu for "More Actions ..." sometimes does not work - all the options in it vanish!

Here are the steps to recreate the problem.

1. Go to inbox.
2. Select the drop down "More actions ..."
3. Instead of selecting one of the options, click on a mail instead. (i.e., outside of the drop-down menu)
4. The mail does not open - which is correct. And the drop-down menu closes - which is also correct.
5. Now select the drop down menu again - the menu does not open up, it does not show any options.

OS: Win 2000 SP2
Browser: Firefox 0.9.2
User Agent String: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040707 Firefox/0.9.2