How to stop Vim from highlighting lines 73+

I am slowly developing my .vimrc and would like to know how to turn off the highlighting (black text on orange background) which starts at line 73. This doesn't seem to be controlled by any selected/customized colorscheme.

I do CFD, and some older codes I use are written in F77, for which this highlighting is useful as a warning. However all of the new code I am writing is in F90 and it is a hinderance because it disables all other text colorations. Is there anyway to turn this off for just .f90 files? Or all files, (the frustration it causes in F90 isn't worth the benefit for F77.)

Also, Vim insists on highlighting tabbed regions with RED. I was able to avoid this with a kind of back door approach of including

:set expandtab

in my .vimrc file. My interpretation is that this tricks Vim into not recognizing the tab, b/c it becomes 6 spaces. Unfortunately, inorder to erase or move the cursor across (I am still learning all the fancy Vim cursor manipulation), it takes 6 keystrokes. Is there anyway to actually tab, and not have it turn red?

Thanks!
DrBones

I can't answer the highlighting of lines above line 72?

To make moving around the text in vi/vim remember that when in command mode:
w - moves the cursor forward by a word (or across all the white space to the beginning of the next word) at a time.
$ - takes you to the end of the line.
0 - takes you to the start of the line.
^ - takes you to the start of the text.

thanks,

I actually found a visual 'cheat sheet' for Vim command when I was searching for this highlighting issue: Graphical vi-vim Cheat Sheet and Tutorial

(It's already stapled to the wall behind my monifor)