htaccess and an unrelated subdirectory

I have three sites on BlueHost: (1) an old site of my academic work, etc. (static, XHTML, etc.), (2) a Drupal site that I initially had at the root of public_html, and (3) an Omeka site.

When I had the Drupal site at the root and the Omeka one in a sub-directory, I had no problem with the static site (which had no .htaccess file). When I switched them to put Omeka at the root, the static site oddly stopped finding anything other than the index.php file. Depending on what settings I tried (by putting a complete or partial .htaccess file into the static site's sub-directory), it either gives me an error (e.g., 500 Internal Server Error) or claims to be at a different page, while still actually being at index.php. Yes, I've tried re-naming the static site's index.php to default.php!

RewriteEngine on

# from Omeka's .htaccess (in public_html),
# replicated in an .htaccess file for static site
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* index.php

# replacing with bits of the following
# from Drupal's .htaccess didn't help,
# despite being in play with Drupal at root

# RewriteCond %{REQUEST_FILENAME} !-f
# RewriteCond %{REQUEST_FILENAME} !-d
# RewriteCond %{REQUEST_URI} !=/favicon.ico
# RewriteRule ^ index.php [L]

This ended up migrating to the dev list, closing here.