What is your TERM env set to?
I tend to have mine set to either xterm or vt220, which lets the syntax
highlighting and coloring come through. Does color-ls colorizes your ls
output?
If vim doesn't fire up in colorized mode, I'll usually exit and try it
with (under bash):
$ TERM=xterm vim somescript.pl
That will set the term type to xterm for just that one command.
But my 'screen' command is aliased to start with vt220 as the default
term type:
alias screen='screen -T vt220'
which works fine for everything except when I try to run vim under sudo,
the highlighting works, but colors don't, so I do the TERM=xterm trick
above, which makes the colors show up again.