WordPress Query Breaks Navigation

This is an alternative to my recent post WordPress Blog display using the more tag
as that method worked on my testing server but it decided to give me 404 errors whilst navigating.

Differences

Instead of changing my home page to display 1 post I decided to change my archive.php to display 5 posts. First and foremost I changed the Blog shown at most settings in admin to 1 as it was this that was causing my problem. I then removed the query to show 1 post from my index.php as shown below.

I opened up my archive.php and placed the following query below get_header to display 5 posts in my page

This has been tested this in archives.php and search.php with and without the WP pagenavi plugin without any problems

Sources

• Showing multiple posts on Archive page

<?php if (is_home()) {
$page = (get_query_var('paged')) ? get_query_var('paged') : 1;
query_posts("showposts=1&paged=$page");
} ?>