[SOLVED] Widget Category drop down menu won't work

I've been searching the Internet all morning for an answer to this and no luck. So I'm posting to the forum in hopes of resolving this problem:

I'm trying to show a list of categories in the sidebar of ATA. To do so, I'm using a category widget.
I've used the regular category widget that comes with wordpress as well as The AVH Extended Category widget and the dynamic widget. All have the same problem.

If I display the categories as a LIST. They work fine and clicking on any category item will display posts relative to that category. But as soon as I make it a DROP DOWN MENU, it no longer works. When you open the drop-down menu and click on any category item, the posts do not change.

I have another website with the same material and it works as a drop down menu. I have opened both sites in two different browser windows and compared all settings. Still, it works on one site but not on the other.

I've reinstalled wordpress 3.2.1 and am using ATA 3.7.1 on both sites.

Any advice greatly appreciated.