I know - you would think the back is okay. I thought it was. But yeah, the vents are there, and the heatsink for the graphics card and the cpu runs behind those vents. There was coffee congealed in part of the vent, which I cleaned out, but some must have gotten in. From what I am reading online it looks like the graphics card has taken the brunt, and considering I use the laptop for editing film, the graphics card is the thing I use most!
I may have to open it up and see if I can clean it. Hopefully that will do the job. But I'm sure opening the thing up won't be easy.