Unity Hangs on Startup with minimal log (Win 7)

Hello all,

We have a Unity 4.1.5-based application, and on one user's Windows 7 computer, the application starts and then hangs without even opening a window.

The process is stuck at 25% (using 100% of one core in a quad-core computer).

Here is the log:

 Initialize engine version: 4.1.5f1 (ed5ea3281df6)
 GfxDevice: creating device client; threaded=1

It only happens on their computer. I've searched on the web, but all other logs seem to get past this point, even those that have graphics issues. Has anyone seen this? Could it be a basic graphics driver issue?

Thanks