MSI GTX 280 OC CoD WaW Intermittent Lockups!

I have noticed that after patching to version 1.3, my game locks up completely and the graphics card fan drops back down from 100% to 40%.

Most of the time I can minimize to desktop then click on CoD WaW in the taskbar, which brings the game back up and running, suprisingly enough most of the time I'm still alive.

Some of the time, the game locks up completely and is not recoverable and must be closed through task manager.

So far I have noticed that the game only freezes when my graphics card is running higher than its standard overclocked settings, but it has only been freezing since applying patch 1.3.

My system specs are as follows:

CPU: Intel C2D E8500 @ 4.27Ghz
RAM: 4 GB Corsair DDR2 1066 @ 1080Mhz
GPU: MSI Nvidia GTX 280 OC - Stock 650/1300/1150, Highest OC 715/1430/1280
MB: Gigabyte GA-EP45-DS3P
PSU: Zalman 850W
OS: Windows Vista Home Premium x64 SP2
Connection: 8MB/128KB Cable in Australia

I have the GPU fan set to automatically go to 100% when the GPU hits 62c, doesn't break 70c (critical @ 105c).

Anybody else getting this intermittent problem of the game freezing after roughly 30 - 60 mins of multiplayer?