I have at one SONY VAIO Laptop GRV-550 with PIV, 512 MB and 16" SXGA. Have One and Half year with this Laptop but the last two weeks When I am running Hard Applications like Photoshop, P2P, AutoCad, I hear that Fan start tu run more fast and the Laptop Turn On....Don't know if is a HDD , MotherBoard or Software problem ???
Sounds to me like you just need to Get some canned are and clean out the vents. :)
Hmm, it could either be dust build up in the cooling system, or the Fan is starting to die. Either way you might need to take it apart and clean the heat sink, and possibly oil the fan.