mod_rewrite - странная штука в Kubuntu 8.04

Есть apache2, с установленным mod_rewrite.

В конфиге apache.conf:

# Include module configuration:
Include /etc/apache2/mods-enabled/*.load
Include /etc/apache2/mods-enabled/*.conf

vir@home:/etc/apache2/mods-available$ ls *rewrite*
rewrite.load
vir@home:/etc/apache2/mods-available$ cat rewrite.load
LoadModule rewrite_module /usr/lib/apache2/modules/mod_rewrite.so

Как только в .htaccess пишу RewriteEngine on, вижу следующее:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, mail@vir.uz and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.

Что это может быть?