Laptops are essential in my lectures and tutorials. I would be running Word, Powerpoint, and possibly Firefox at the same time. Since this can be tiresome on your battery, I'd generally have my power adapter hooked up too. However I tend to get this loud fan noise every now and then (whirring noise). Sometimes it will last upto a minute and then it just stops. Its a bit of a nuisance when you're in your tutorials.. Any thoughts?? Thanks in advance..