I had a strange problem today. I wanted to show a block on homepage only. So I went to the Block and added "" and clicked the box "Show only on listed pages". You would think this should work. But when your website has "node" as front page and if you have 10 pages of Nodes, the block will show on all 10 pages and not just the home page
This is a weird problem, I tried many combinations, until I figured out that you have to put the following PHP Code and select "Show only if PHP code returns TRUE"