Early 2009 fans staying at 2k rpm

Hi, just to start out, let me mention I have experience repairing logic boards so I just need pointers as to what to repair on the logic board.
This computer is a macbook pro 17" 2.66ghz core 2 duo from early 2009. out of warranty.
Basically this machine works fine no problems until it gets hot. Machine will freeze and the fans stay at 2000RPM.
I've already done all the resets as per the book. SMC/PRAM.
Computer is up to date software wise running 10.8.2

I have fan control running to increase the rpm up to 3600RPM which makes the machine run great no problems.

I will be taking apart the machine and re-applying new thermal paste. Any other ideas?
thanks

It's kind of hard to know what would be causing the "freezing" of the computer without more information.

Has the ram been upgraded at any time? has liquid been spilled on it at any time?

- Nick

Problem solved!
I took it apart and took out the heatsink.
Removed the old thermal paste and cleaned out the chips as well as the heatsink with alcohol 99%. This got rid of all the gunk. Note you need to use a flathead tool that won't damage the chips in order to remove the solid stuff. Once those are removed you can then wipe it with toilet paper or similar dipped in alcohol.
Heated up the cpu/gpus in order to do a quick reflowing - just in case something had been slightly damaged from the heat.
Took a look at the heatsink and retouched up the thermal sensor with a soldering iron/flux.
Reapplied new thermal past - Artic silver.

Put back together. pram/smc reset.
Turn machine on and go to youtube and open multiple tabs/videos.
Machine never got hot and fans sped up as they were supposed to.
No problems so far. No need to fan control anymore!

Congratulations…problem solved!

- Nick