xhost: unable to open display ":0.0"

[jbk]

# su -
-bash: \e[3~:delete-char: command not found
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified

xhost:  unable to open display ":0.0"

This symptom occured after upgrading Fc3 to Fc4. It only 
happens when I login as root locally. If I SSH from another 
machine and then 'su -' I have no trouble.

"xhost +localhost" is defined in root's .bash_profile.

A fresh install on my laptop did not exhibit this problem.

I am googling the mailing lists but have yet to find 
reference to this particular circumstance.

Jim