You could do several things, here's a few:
- drop the href="" attribute <a onclick="showdiv('fadedbg'); showdiv('popup');">My Tasks</a>
- use span instead <span onclick="showdiv('fadedbg'); showdiv('popup');">My Tasks</span>
But of course, span tags don't have the nice :link, :visited, and :hover pseudo classes.
I always take advantage of <a> tags for this reason.
Since you're not actually navigating anywhere, the anchor tag <a> doesn't need the href="" attribute.
Here's an example:
Since I added "return true;" to your function, the onclick attribute is testing for "false".