iPhoto 6 keeps suggesting to me that I should rebuild my thumbnail cache. I let it do so. But a day or two later I get the same prompt again, telling me to rebuild my thumbnail cache. I've rebuilt it a few times now. This started only after I upgraded to iLife '06. It is NOT the result of crashes out of iPhoto, since it happens after a clean exit and relaunch. Nothing seems wrong if I decline its offer, but I'm worried about why this happens. I'm ... not ... alone ... but I'm still puzzled about what's going on.