[support] Clean urls

I'm having an issue getting clean urls to work. I'm set-up on a shared hosting plan, and my host verified mod_rewrite is already enabled on the server side. I tried different settings in .htaccess, but nothing seems to work. Here's the interesting part: When I run the "clean URL test" it passes and the radio buttons to enable clean urls become functional. However, after selecting enable, then clicking save configuration, the selection defaults back to disabled.

My drupal install is located in a directory called httpdocs, which I was told is equivalent to /var/www. I did not put the drupal install in a folder of its own, rather I just installed all the files in the httpdocs directory.

Any ideas or suggestions?

Thanks,

Troy