Mod_rewrite help

(I accidentally posted this in the Beginner’s Forum.)

I’m developing a PHP message board/forum, and I’m making use of .htaccess and mod_rewrite to use “pretty URLs”. For example, the URL to my user profile would look something like this:

…instead of the usual query string mess like the following:

The directive used to get this looks like this:

RewriteRule ^profile/([\w+]+)$ profile.php?user=$1 [L]

On my home testing server everything runs fine. But when I put it up on the DreamHost server, mod_rewrite seems to be acting weird. All of the “static” rules are working fine, but in any RewriteRule that contains “dynamic” things like ([\w-]+) or (\d+), the server redirects me to my 404 error page.

Any ideas on what could be the problem? I’m probably being pretty vague, so I can give out more information if needed.