It may be a coincidence, but ...
After upgrading to LR2, my system won't recognise Ubuntu (Linux) or anything outside the Windows partition. It won't boot Ubuntu or diagnostics from a live CD, and Windows says it's unable to complete Scandisk but gives no reason.
As I say, it may well be a coincidence, but the alternative is that my hard drive is starting to give problems. But it's only 6 months old, so that's also unlikely.
So I thought I'd ask the open question and help to swing the odds in one direction or the other.