There is a weird Google bug with the cache feature. It seems to only impact home pages. For example, a search for this site in Google returns a Google search result of the home page (we aren't penalized yet):
But when you click on the cache link, it takes you to a dead page:
This does not appear to impact inside pages, but rather only the root page (aka home page). Why?
I have been receiving emails reporting this, as well as spotted several threads in the forums about this. Threads come from Google Webmaster Help and WebmasterWorld.
I should note that this isn't uncommon and I wouldn't worry about this impacting your Google rankings.
Forum discussion at Google Webmaster Help and WebmasterWorld& HighRanking Forums.
