I was having a problem getting clean url's to work after moving to another hosting provider. I'm using Drupal 4.7rc3 right now and I just couldn[t figure out what the problem was. I knew that ModRwrite was enabled. I had the right commands in my .htaccess file. I was stumped. I found this comment on Drupal.org that solved the problem for me.
The answer: Just add a slash in front of index.php in the rewrite rule like this:
RewriteRule ^(.*)$ /index.php?q=$1 [L,QSA]Now it works just fine.