Load an applet with an animating gif in it;
Leave the page and return to it again;
Animating gif does not appear any more.
Also happens when you load an applet with an animating gif in it, leave page, and then load a second applet with another animating gif in it.

For example, go to
http://javaweb.eng/~mukundm/BrowserSuite/BrowserSuiteVerQ/Suite/QLhtml/6/8.html
then to a non-applet page; and then again back to the same page above; or go to the Toggle buttons tab in SwingSetApplet at
http://javaweb.eng/~mukundm/BrowserSuite/BrowserSuiteVerQ/Suite/QLhtml/1/4.html

Noticed in the P and Q builds; may have happened earlier too.
Happens with Netscape and IE4; on Win 95 and NT.