Google caching the wrong page

[HelpRequired]

I am very confused and concerned by google as it has cached a completly different page from the one that it should have, ie the page that the URL is related to.

When i did a search this morning i found my page in second position, which is normal. However, rather then showing up with the page title and meta description it was just giving the pages URL. I then clicked through to page (which is correct) and did a cached snapshot and it brought back a completly different page, saying it was cached on Sept 29th. The page it brought back is the homepage of the site, so i am thinking perhaps when it cached the page is didn't crawl beyond the main site URL, ie didn't not go past the / is this possible?

Obviously i am very concerned as it is effecting how much search results appear in google and no dount if this error continues will cause the page to bomb out completly.

Has this happened to anyone else and what can i do?