The community is also a great place to check out. Try these places for help from other users:
This game requires Games for Windows Live for authentication purposes. If you are encountering an issue when launching or connecting to Games for Windows Live, or you have lost access to the Games for Windows Live account this game was activated to, you will need to contact Games for Windows Live support to troubleshoot the issue or recover your account.
Dark Souls: Prepare to Die Edition is not protected by the Valve Anti Cheat service. If you encounter a player that you think is cheating, you will need to report that player to Dark Souls support.
If you're encountering issues with launching Dark Souls Prepare To Die Edition, make sure everything installed smoothly.
Exit Steam entirely.
Browse to your Dark Souls Prepare To Die Edition installation folder (Usually C:\Program Files\Steam\steamapps\common\D:\Steam\steamapps\common\Dark Souls Prepare to Die Edition\)
Run the following installers:
Reboot your computer and test any issues again. If the issue persists, contact Dark Souls support.
If the above does not resolve the issue and you are running Windows 7 or Windows Vista, please complete the instructions in our Windows 7 and Vista Troubleshooting FAQ.
If you are running in Windows XP, take the following steps: