query_posts + showposts + permalinks = 404

[wp_guy]

So, apparently when doing something like query_posts($query_string.'showposts=2'); in a category.php file for example. Everything seems to work fine, but the paging doesn't, I get 404 errors on the 3rd page.

Here is how the blog is setup:

• 'Blog pages show at most' is set to 5 in the settings
• category.php has a query_posts($query_string.'showposts=2');
• the category I'm browsing contains 7 posts.
• permalinks are set to 'month and name'

Here is what I do:

1. myblog.com/category/mycategory works fine, shows 2 posts
2. myblog.com/category/mycategory/page/2 works fine too, shows the next 2 posts
3. myblog.com/category/mycategory/page/3 returns a 404 error.

The above works just fine if I use the default permalink structure (query string).

I've seen this error in 2.6.3 and 2.7, haven't tried on earlier versions