Well see the thing I was noticing on your pages is that the actual content links aren't there. I didn't see any links in your content areas that were linked to the alphabetical menu you have setup. It does seem to work in Firefox, not sure how lol, but looking at your code it seems that it's missing each of the tags that need to be positioned in the page near the actual content being linked to.
If you can take a look at the code of my page in the link I gave earlier, you will see that it takes a little practice and a little trial and error to get the links right where you want them also. I didn't get them right off the bat either hehe, I had to play with the positioning until I got it to go exactly where I wanted it on the page. This means that it doesn't always go at the top of the actual section (in your case sample letters) and may need to actually be positioned a bit higher on the page or lower etc.
Take a look at Zacs test page too and see if between his made in VSD and mine in HTML Editor you can find a happy medium on it. Using the HTML Tool definitely sounds like what is needed which I wasn't sure about so that's all good to go, just gotta get the code correctly on the page is all.
I'm not seeing anything wrong in the code for it either which isn't helping, maybe try making your menu not be a scrolling menu and see if that is maybe what's messing it up? Maybe there's something in the script for the menu that is causing it.
P.S. Don't forget to include links back to the top of the page also (anchor tags also) so people don't have to scroll all the way back up manually.