Edit: Checked today and search from the nav bar is working again 1st October 2009
While looking for an old post noticed that the blogger nav bar search is not working properly. It will sometimes find search terms that are in the title of a post but not search terms in the body of a post.
It turns out that this is a problem effecting many blogger users and has been so for about a month.
Google are aware of the problem. There is a link from the link above where you can fill in a form with details of your site if you are effected. Hopefully the more that fill in the form the quicker google will get it fixed.
It seems that the problem is also with the google search gadget that you can add in Blogger layout so if you are using this it would be worth checking that it works.
Polybore has worked around the problem (to an extent) by using adsense to create a custom search limited to polybore.co.uk. (You can see this above the post section). It does the job albeit in a rather clunky fashion.
Having said that it does the job, the results are far from ideal. Search results for older posts seem to be getting lumped in together. Bit worried that this is some sort of blogger related archiving problem. (will investigate).
Am considering removing the navbar to prevent confusion but am hesitant to do so because not sure if this would be a breach of blogger TOS.