When an iBook is sleeping isn't generating much heat. That's why you can leave it on for HOURS and come back and find the battery charge at about the same level. I've always used a laptop case and never had any problems. Ron On 7/10/05 8:34 AM, "Samantha Cornell" <samantha at netresults.biz> wrote: > Does anyone have any idea if this is okay? Will the case impair the > cooling to such a degree t hat I should be concerned?