[support] htaccess regex could not be compiled; 500 internal server error

Details here: http://drupal.org/node/1972900 D7 is fine on my local Ubuntu, but when I try to install it on a shared hosting environment where I have D6 installed w/o problems I get an error. Error log says htaccess: regex could not be compiled If I comment out the FilesMatch section or replace it with the D6 FilesMatch, I do not get the error. I get the same error/no error result even if I just place the .htaccess file in the www root without any other files in it.