This afternoon I was at an Apple Authorized reseller (no Apple Stores where I am) and they are the kind that have an attached service center. I was there for something unrelated but still took out my laptop. Anyway, as I was packing up the computer to go, the guy saw that I just put it to sleep and didn't shut down, and told me to 'watch that because with all the magnetic fields around nowadays, it could wake up any time since the sleep mode on macs works using magnets, and then since the first thing the computer does on waking is to read the hard drive, you could damage the drive by having it being read while you're moving the computer around'. Well, that's not an exact quote down to the it's and the to's, but that's pretty much what he said. He went on to advise that the only proper way to do things is to ALWAYS shut down completely when transporting the laptop. Otherwise, he said - rather ominously - I should make sure I back up daily to prevent excessive loss of data should my drive fail on me. What I would like to hear some views on is this: how big is the risk, in real world conditions rather than in theory? I mean, he said that it does not happen with EVERY magnetic field, but that there is no way to know which is going to do the trick. And he also recognized that it does help if you don't jostle the laptop when transporting it (eg, you don't run to catch the bus with the laptop in your bag). So, putting these two together, how likely do you reckon it really is that you will a) happen on one of these magnetic fields that is the right type/strength to wake your laptop, then b) also manage to jostle it at the same time before it's had a chance to go to sleep again and c) jostle it enough to cause real damage? I know this is probably not the kind of situation were I should expect absolute answers - as in, NO, there is absolutely no risk, or YES, it's as good as certain. All I am hoping for is a relative answer - a bit of risk assessment: to see whether not shutting down my laptop for every 20 minute walk is an unreasonable risk. See the thing is, while in theory I have no objection with shutting down entirely, I know that in practice it is going to be sheer hell because it will actually entail a pretty massive change in my routine - a routine that's served me very well for years So I don't want to put myself through the hassle of such a change unless there is good cause to do so.