Permalink Problem

Still having trouble. Really at a loose end here, have been all over Google, tried a couple of other forums, no response there either. Not sure what to do.
I’m 99.9% certain my webhosts (who use Apache) allow mod_rewrite, I have tried removing the trailing slash from RewriteBase and all sorts of other suggestions I’ve seen in forums and on the Wiki for this kind of problem (although no-one seems to have had this specific problem).
I’ve even tried ditching smart permalink strctures altogether and just using the default setting with the post ID but the same thing happens even then: When I click the permalink to an entry, I get taken to a page with a blank post, which just has the date and title etc at the top, and the comment box at the bottom but no post in between!
I’m using the structure /archives/%year%/%monthnum%/%day%/%postname%/ and here’s whats in my .htaccess file
<ifmodule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteRule ^archives/category/(.*)/(feed|rdf|rss|rss2|atom)/?$ /blog/wp-feed.php?category_name=$1&feed=$2 [QSA]
RewriteRule ^archives/category/?(.*) /blog/index.php?category_name=$1 [QSA]
RewriteRule ^archives/author/(.*)/(feed|rdf|rss|rss2|atom)/?$ /blog/wp-feed.php?author_name=$1&feed=$2 [QSA]
RewriteRule ^archives/author/?(.*) /blog/index.php?author_name=$1 [QSA]
RewriteRule ^archives/([0-9]{4})?/?([0-9]{1,2})?/?([0-9]{1,2})?/?([_0-9a-z-]+)?/?([0-9]+)?/?$ /blog/index.php?year=$1&monthnum=$2&day=$3&name=$4&page=$5 [QSA]
RewriteRule ^archives/([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/([_0-9a-z-]+)/(feed|rdf|rss|rss2|atom)/?$ /blog/wp-feed.php?year=$1&monthnum=$2&day=$3&name=$4&feed=$5 [QSA]
RewriteRule ^archives/([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/([_0-9a-z-]+)/trackback/?$ /blog/wp-trackback.php?year=$1&monthnum=$2&day=$3&name=$4 [QSA]
RewriteRule ^feed/?([_0-9a-z-]+)?/?$ /blog/wp-feed.php?feed=$1 [QSA]
RewriteRule ^comments/feed/?([_0-9a-z-]+)?/?$ /blog/wp-feed.php?feed=$1&withcomments=1 [QSA]
</ifmodule>

Thanks, I have changed my permalink structure to /archives/%year%/%monthnum%/%day%/%postname%/ as you said.
I want to call my blog using
http://www.site.com/blog/archives/2004/09/30/hello-world/
….so I used RewriteBase /blog/
I did try and store my .htaccess at http://www.site.com/.htaccess like you suggested but the thing is, if I do that I get a 404. It only seems to recognise the .htaccess file if I store it in the /blog directory.
What do I need to do about my “WordPress” and “blog” URI settings?

wenchy are you sure mod_rewrite is active/allowed on your server? Or that .htaccess files are allowed to override apache’s default config settings?
This probably doesn’t matter, but make sure the .htaccess is saved in Unix file format and not PC format.
Try the following inside your .htaccess:
<IfModule mod_rewrite.c>
INSERT REWRITE CODE HERE
</IfModule>

I have tried that and it doesn’t work.
I’ve just written to my webhost to double check that mod_rewrite is allowed, and whether .htaccess files are allowed to override apache’s default config settings.
Will post the response.