Q: My Macbook Air's fan, and many other features, have been acting up lately.

Hello! I purchased my Macbook Air back in December, and after having it for a good 6 months I'm beginning to run into issues.  Out of the blue, the inside fan begins going with full power (usually only happens when I'm streaming something HD or doing tons of tasks at the same time) even if I'm only running something like Pages, or even when I have quit everything and relaunched Finder. Also, as soon as the fan kicks on, all tasks begin to respond very slowly - typing, moving the mouse, ect.  This has been happening for a few days now, and the fan begins blasting anywhere from 30 seconds to a minute after I start up/wake up my computet and sign in.  Other info: I have no large files on my computer (just Pages docs and screenshots), and the only things I have downloaded are Firefox, Spotify, Silverlight, and Adobe Flash Player.  I would very nuch appreciate help with this issue. Thanks!