I've only tried launching through Steam. I don't have SixLauncher installed on this machine.

Okay! Found a fix for my issue.
I was running DirectX 10, however my graphics card supports DirectX 11
I'm running Vista, and the download for the 32bit version of DirectX 11 is posted below.
http://www.microsoft.com/en-us/download/details.aspx?id=3274

Additionally, I was injured next to another downed soldier and was able to drag him. My character model continuously rolled around and I was unable to release him while still downed, even though the 'release' option was available. We were both eventually revived, however, I was still dragging this soldier and unable to release him. Visually, it looked like I was 'carrying' him around, and had no speed impairments (ie. I was able to sprint, prone). The soldier was unable to move but could perform actions like vault or discharge his weapons, but again, had no movement capabilities. To quick fix the problem we tried a few things. First, I got into a helicopter, thinking the game would split us. I was still given an option to 'release' the soldier and it did not work. Also, he was stuck to the outside of the helicopter. Next, we brought in some other soldiers to shoot us, only to discover that the soldier I was carrying was invulnerable. The problem was fixed once I was killed. The soldier was free to move, and I no longer had the option to 'release.'