"Failed to create D3D device" crash in Source games

The latest problem I was asked about was a crash upon startup of a Source game. I encountered this problem myself quite some time ago, so it was an easy fix to help that person. May as well throw it up as the first help post on this blog.

Most famous of the source engine games developed by Valve is Half-Life 2, but the error can be from any of these Valve games:
Half-Life 2
Half-Life 2: Episode 1
Half-Life 2: Episode 2
Portal
Counter-Strike: Source
Team Fortress 2
Left 4 Dead

And more.

If you're getting this error, you probably have an ATI graphics card. The crash likely comes from using the official ATI drivers obtained from their website.

Before the ATI drivers though, you should make sure you have the proper Direct X version installed. For Windows XP, this is Direct X 9.0c.

Step 1
Download and install Direct X 9.0c for Windows XP

Now that you have made sure that Direct X is up to date, it's time to get the proper graphic card drivers. One would assume the best ones to have installed are the official ones, but that isn't quite the case, especially if you are getting this error.

Omega Drivers are the best. It's very likely installing these will fix this particular problem.

Step 2
Download and install Omega Drivers for either ATI or NVIDIA, depending on your brand of graphics card.

Now, that will likely solve the problem with crashing Source-engine games. If it doesn't, or you are encountering this problem with another game, contact me and I'll do my best to find an answer for you.