I have recently installed Redhat 7.1 on my machine. The X
window system works all right, but the desktop is not centered
on the screen. I tried to run "xvidtune", but is terminates
with the following error message:

Error: Can't open display:

I ran it as root, with Gnome either inactive or running.
How can I run this utility? Or is there any other way to adjust
the size and position of desktop?

You run that utility as the logged in user.

Thank you, it worked.

You probably invoked xvidtune in root's environment, which likely
doesn't have the proper DISPLAY and XAUTHORITY variables set.
Next time, before you run xvidtune, try setting these:

export DISPLAY=:0.0
export XAUTHORITY=/home/[your_username]/.Xauthority

Then run xvidtune.

Alternatively, instead of getting your root shell with "su -" in
your xterm, use plain old "su" so the xterm retains your DISPLAY
and XAUTHORITY settings.

Most monitors have display controls that might help with minor to
moderate corrections.

--

-John (John.Thomp...@attglobal.net)