I have a chunk of code here that's starting to really bug me. I know I ran into this problem in the past, but my resolve escapes me at the moment

I re-wrote a very basic version of this code so you can see what's happening:

Code:
<div onmouseover="javascript: mainmenu.src = 'gfx/Animation1.gif'" onmouseout="javascript: mainmenu.src = 'gfx/frame01.gif'">
 <img src="gfx/frame01.gif" name="mainmenu">    
 <br>
 <a href="#NULL">Option 1</a><br>
 <a href="#NULL">Option 2</a><br>
 <a href="#NULL">Option 3</a><br>
 <a href="#NULL">Option 4</a><br>
</div>
The onmouseover in the div swaps the image with a single-pass animation, basicallly a lighting effect that turns part of it blue.

Now the problem: every time I pass over a link within that div it resets the onmouseover and plays the animation again. Is there any way to avoid this?

Any ideas would be very helpful, I know there is a way but I can't remember if I just did a hack job to get things working before.

Thanks