Extreme Game Lag on Every Setting

[Drone37373]

I am presently using a Gateway NV55C49U laptop.

Specs
Intel® Core™ i3-370M processor 2.4GHz
3GB DDR3 install memory
320GB 5400RPM Hard Drive
Windows 7 Home Premium 64-bit
15.6" LED-LCD high-definition widescreen display
1366 x 768 resolution
Intel® HD graphics

The Intel Driver was updated from the Intel website. It is current.

The game was downloaded through Steam.

It is somewhat strange what is happening now:

I used the game to automatically detect my settings and it was set to "medium". The game ran smooth and flawless for the first 15 minutes or so of game play which was great. I then later opened up the game from where I left off and started to experience some lag. As the next 10 minutes went on the lag got terrible. I then also experienced issues with the game. I picked up a note and when Daniel had the flashback about being stuck in the tomb but saw some light, the screen just went black and I could hear the game sounds but could not get out of it. Now, the game lags extremely bad regardless of what settings or resolution I have it set to. I have tried every option. I have lowered the settings all to 'low' as well as disabled all of the extra options possible yet the lag stays just as bad. Strange how adjusting the settings now doesn't even affect this.

Any help at all would be greatly appreciated. I love this game so far and would be thrilled if I could continue playing.

Regards,

Chris