The orgional post (if you for some reason want to see it...?) can be found Here.

Alright so I assume you were having a problem like me (or similar). I would open up RB6:L it would say I'm in game, yet I was still sitting on my desktop/steam and the only way I could attempt the game again was to end it via Task Manager. I didnt read till later that Windows 2000/XP was suggested and nothing about Vista, 7 or 8 (8 wasn't out yet at the time I found this fix).

Before going any further, just to be on the safe side of things make sure you:

• Update to latest graphics card drivers
  
• Updated DirectX files (even having older ones will help the game out in most cases) Also an older install of DirectX will never overwrite newer ones (so DX 9 install wont overwrite/get rid of DX 11).
  
• I think in some cases peoples Anti-virus software can cause issues, try disabling it for 10 mins or so and then trying to run the game.
  
• Make sure your PC can handle it (not including the Operating system).
  
• Make sure you have at least used verify integrity of game cache once.

Go to the Game Copy World's site Which can be found Here[gamecopyworld.com].

Click on any of the mirrors that are in good to go (either in green or orange in this case should be fine).

Next read all of that stuff (if you want) and click on Enter when you have/haven't.

Now look to the right you should see "Game Index" click on that or select one of the letters.
Once your in the Game Index page, look for "Rainbow Six: Lockdown" in the R section, or type it in the Game Index's search address. Once found click on it.


Now download the one that says "Rainbow Six: Lockdown v1.01 [ENGLISH] No-DVD/Fixed EXE" it will scan you down the page to where you can download it.


Click on the little blue floppy disc to start the download link.

Alright so you should have a file called "T-r6ld11.7z" in which you need either 7zip or Winrar to open it (google them). Double click on it to view the contents of the zipped file.

BEFORE EXTRACTING ANYTHING!
Locate where RB6:L is located (default location for 64bit systems "C:\Program Files (x86)\Steam\steamapps\common\Rainbow Six Lockdown") and make a new folder and name it backup (or anything) and copy "lockdown.exe" and paste it into the new folder that you had just made.

(You dont have to backup as you can get the steam version of the exe file back by clicking on verify integrity of game cache).


Now is the time to replace lockdown.exe with the one you downloaded just before.
*Note: I havent had the game installed, so I've gone to install it (and will take too long to install) so It the location on where your game is installed WILL be different.*

Either click and drag the lockdown.exe file from the zipped file or extract it to where RB6:L is installed and you should get a message asking what do you want to do with the 2 files (replace, dont do anything or rename).
Say yes (first option) and allow it to be replaced by the downloaded exe file.

Alright thats all there is to it! It should now load fine (I dont know why or how but it does!).

One thing to keep in mind, if you for some reason click on verify integrity of game cache that will replace the downloaded no cd exe with the steam version (and go back to not working I'd assume)
So keep that in mind and hopefully this fixes it for you!

Another note: If you have 2+ (I'll assume anymore then 1) screens, getting into the game works fine but each time I started a mission, I would get a black screen with sound in the background until I alt+tab out of the game and back in and who wants to do that each time they played the game (or every mission I never tested that). But if you do and can put up with it, keep that in mind.

It might of been the resloution I was using too, dont remember if it supported it.

To get around this problem, just disable/unplug 2nd screen and run the game.

Questions, or any feedback is welcomed!
Thanks for reading!

If this guide hasn't helped you, not all hope is lost! The Ubisoft Devs have reached out to give some help.

"we're often able to help troubleshoot further with the help of some system files[www.ubisoft.com] - a DxDiag.txt and an MsInfo.txt. The article I've linked there will show you how to find each of them.

Once you have those files, you can reach out to us via our support website[www.ubisoft.com], or via Facebook PM[www.facebook.com] or Twitter DM, to send them across, and we'll be able to use them to investigate why the game's not starting up.

- Ubisoft Support"