Thanks for your suggestions.
Yes, my host supports PHP.
I use filezilla.
I did create a script calling phpinfo(), and here is the beginning of the page :
PHP Version 4.3.10-2
| System | Debian GNU/Linux |
| Configure Command | ./configure |
| Server API | CGI/ProXad |
| Virtual Directory Support | disabled |
| PHP API | 20020918 |
| PHP Extension | 20020429 |
| Zend Extension | 20021010 |
| Thread Safety | disabled |
| Registered PHP Streams | php, http, ftp, compress.bzip2, compress.zlib |
As for a problem with .htaccess, I'll tell the host about it. But I wrote them an angry email yesterday, so they might not want to help any further (not that they helped much so far...)
Corinne