[support] clean URLs is greyed out

[Miles Fidelman]

I'm in the middle of a brand new Drupal 4.7.6 install.  When I try to 
enable clean URLs, I find that the radio box is greyed out.

The thing is: mod_rewrite seems to be working, and the clean URL test 
works, and I enabled the path module and gave myself permissions to do 
everything.

Any suggestions?

Thanks much,

Miles