Pagination linking to post with the page number in the title

Hi,

I’m having an issue with pagination on a multisite install. It crops up in most if not all themes on this particular install.

The pagination link for page 2 goes to a post with the first letter in the title being 2. Page 3 goes to a post that starts with a 3 and so on.

Pretty permalinks work fine.

Can anybody point me in the right direction? I’m pretty stumped.

thanks,
d