I will answer my own question. I called tech support at hostmonster.com and the second guy I spoke with was very helpful. He looked at the .htaccess file in the /subdir and saw that SimpleScripts had not properly configured it. He edited line 2 to read:
RewriteEngine On
RewriteBase /~username/subdir/
Substituting the actual username and subdir for the placeholders I wrote above.
I have the same problem but a different setup. The site is hosted by hostmonster.com, so I can edit the .htaccess file (or create one if necessary)–if I could learn what the .htaccess file should say. In my root directory is an installation of WordPress MU. The domain does not yet point to hostmonster.com’s name servers so I must access the WP installation and the wp-admin files via the IP address. This works fine and I don’t want to mess what I have there. In a subdirectory off the root, I did an installation of BuddyPress. http://[ipaddress]/~username/subdir shows me the front page of Buddypress the default theme. But all of the links result in 404 errors. They are looking for http://[ipaddress]/~username/subdir/activity or http://[ipaddress]/~username/subdir/members, etc. and those directories don’t exist. What am I doing wrong? TIA!
