First, just to demonstrate what's happening, give #maincontent a background color.
When you put absolute positioned #taglinetext, relative positioned #logo(
), and floated #navbar/#twittergroups/#fbgroups ... there is nothing to give #header a height. ...Correction, it does get a bit of height from 50px high #navbarholder.
Just clearing your floats
would normally give #header a height and push your #maincontent down so it's not covering your links but, in your case, the box model rule has not been followed so that doesn't work. See the box model here
. The box model says that whatever you put inside an element cannot be larger than that element. margin/padding/border all count when figuring width/height.
Give #header a height and your content will be pushed down enough that your links will be available again. Kind of a bandaid really since your box model is still off in #header.
When posting code in the forum its [code] and [/code]