Maybe you should try downloading the latest drivers for you're video card or maybe even reinstall the game, make sure to delete the Vegas 2 directory if you do (C:\Program Files\Ubisoft\Tom Clancy's Rainbow Six Vegas 2)!
EDIT: Lethal is right, there is alot of reasons for a blue screen. I'm trying to find out what exactly is causing that blue screen.
If it's only Vegas 2 then you likely have a corrupt game file.
Your temperatures are fine!
If you can run other FPS with no problem, then the issue is with Vegas 2.
I would suggest a complete clean reinstall!
Before you start, copy your PlayerProfile.ini file to another drive or folder.
Find it here:
C:\Documents and Settings\Default\My Documents\My Games\Ubisoft\R6Vegas2
(This contains your key and could save problems later)
You can actually copy that entire folder to save all settings.
By complete I mean uninstall Vegas 2.
Then delete the folder above.
Delete this folder:
Tom Clancy's Rainbow Six Vegas 2
C:\Program Files\Ubisoft\Tom Clancy's Rainbow Six Vegas 2
Delete all entries in you registry that pertain to Vegas 2
Export your entire registry before you start.
Before you reinstall, download this patch! 1.03 Patch
Install Vegas 2
Install the patch
(This will eliminate the auto update and is more secure)
Copy your profile (with your key) that you saved before you uninstalled.
Reboot .. run the game, and pray!
You can also install the map pack and Comcast Event map after you are up and running.