(I am sorry for the length of this post, but cannot make it shorter.) I replaced my faithful MacBook last week with a MacBook Air. I used Migration Assistant to create an image of my old material on the MBA. It took several hours, and the report told me that a file with a to me meaningless name had not migrated. However, the MBA then worked perfectly, save as follows. With the MBA on, and powered up, I plugged my Sony PRS 350 ebook into the USB-drive to charge it. That proceeded normally, and I had no use for the MBA for an hour or so, so I shut the lid. Seconds later, I changed my mind, and opened the lid. The MBA now reported -- wrongly -- that I had disconnected an external device without first ejecting it. On top of that, the ebook froze, and had to be brought back to life with the help of a straightened paper-clip. I ran a hardware-check on the MBA, and was given a clean bill of health. I then went to Disk Utilities, Verify Permissions. This revealed an enormous number of errors. I ran Repair Permissions. Once that was done, I re-started the MBA, only to find, when I went back into Verify Permissions, that there were still an enormous number of errors. I have repeated the process again and again, but the situation is unchanged. Can any kind person help ?