Can someone help me with duplicate homepage issues?

Hi I’m having trouble with duplicate content and I can’t fathom what is wrong.

For my main keyphrase ‘how to quit your job’ I used to rank on page 4 in Google, then for a few weeks I would randomly drop out completely, then reappear a week later back on page 4. This would happen for a month or so then 2 weeks ago I disappeared again never to return. My individual pages are ranking better than ever but the homepage is gone.

In it’s place, I have discovered is a different version of my homepage. This –

Psycholocrazy | How to quit your job, find your passion and live life …
http://www.psycholocrazy.com/page/2 Share 31 Oct 2012 – Do you ever have those days when you just cannot be bothered to do anything? Well I’m currently having one of those weeks and it’s not …

When it should be this –

Psycholocrazy | How to quit your job, find your passion and live life …
http://www.psycholocrazy.com/ Share 3 days ago – Hi I’m Jamie and this is the blog to help you quit your job, find your passion and live life on your own terms. Stop doing what you hate and go …

Notice the correct homepage url and my correct site description.

What I have done –

1. I have All in one seo plugin and I have no indexed my categories and tags and I have canonical url’s checked.
2. I have submitted both www and non www to webmaster tools.
3. I have very reputable high PR websites giving me backlinks and no black hat SEO whatsoever.
4. My site is almost 6 months old and it was behaving fine until about 4-6 weeks ago.

To summerise –

Can anyone give me any ideas why Google is offering up ‘page 2’ as my homepage and stealing a snippet from a random post for the meta description?

Thanks for reading.