Permalinks & 404 Errors

Hi all!

I’ve read all the most recent posts concerning permalinks management and related errors but none of them helped me resolving my strange issue.

First of all, this is the current configuration of the server that is hosting my domain:
– Apache 2.0
– Linux
– PHP 4.4.7
– WordPress 2.3.1
The rewrite module is enabled and htaccess is fully supported (on the same domain I am using custom error pages without any kind of problem). My WordPress is installed in the /blog/ subdirectory but the main page is showing on the domain root (in which I have properly placed the index.php after configuring the general settings about URL addresses).

I’ve selected a custom permalink structure for my brand new installation: /%category%/%postname%/. The htaccess has been successfully built and its CHMOD is 644:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

The problem is that all the permalinks of my blog are returning me a 404 error when I browse it with Internet Explorer 7 (upgraded with lastest patches). With Mozilla Firefox I can see the pages without problems as if permalinks were properly working.

It’s just incredible, and I can’t find a solution. I’ve tried to follow all the fixes proposed in this forum and I’ve also tried to modify the htaccess including the subdirectory:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>
# END WordPress

But the server was returning me an internal error.

If you want to test this issue, you can visit my homepage here and try with RSS links at the end of the page (that still need to be finished). However… any idea?

Thanks in advance!