Permalink problems

Hi
I am havign huge trouble with permalinks, having just upgraded to 3.1

Basically, my front page is fine – https://www.rescue-archaeology.org.uk/
(well not but this is a site wide restore so some things are bound to still be broken)

anyway, all the links show up fine, pages work OK (https://www.rescue-archaeology.org.uk/contacts/) but am having no luck with getting posts to show – just get a 404 page – https://www.rescue-archaeology.org.uk/2011/02/20/rescue-agm/

Have tried al permuatitions to permalinks – the only one that works is default. Am trying to implement Day and Name

HT Access looks as follows:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>