Hi Rob,
It could be a couple things -- module position assignment or blog/homepage configuration -- or a combination of the two.
Are your homepage-specific modules also assigned to the blog category?
Is your home page menu link directly linked to the blog category or is the blog category a sub of the home category?
Looking at the blog category page at
www.rob-brown.com/Blog/Page-1.html leads me to believe it's one of these two issues -- module position assignment or blog/homepage configs.
That's my best guess. Both are easily fixable.