This looks promising: I made a new "Standard user" account on my computer. For some reason google earth seemed to work alright. Figuring it wasnt an issue with google earth, and having temporarily disabled security software to rule out interference I tried downloading ccleaner back on my main account. I wiped the registry, temporary files and all other options, in particular the option for "google earth" under applications. Having done this, google earth seems to work fine. I guess there must have been some leftover temp files causing havoc, even after fresh installs. Lets hope this really has fixed it.