The exact cause of this problem is elusive, but the consensus appears to be that it relates to javascript caching issues (either corrupt caches, or race conditions caused by caching).

The first step that you should take when attempting to solve this problem is to clear your browser cache.

• Firefox: open the Preferences window, select the Advanced page, select the Network tab, and click "Clear Now".
• Seamonkey: open the Preferences window, select Advanced -> Cache, click "Clear Cache".
• Internet Explorer: open the Internet Options window, select the General tab, click "Delete files" in the "Temporary Internet Files" box.
• Safari: select "Empty Cache" from the Safari menu.
• Other browsers: please consult the help documentation for your browser.

You may wish to restart your browser to ensure that no cached information can be retained.

If the problem persists, please contact the support team.