LOL! ver 12, same problem. 5 Months later Ver 13 same problem. Deleting the Cache doesn't work. But oh well. 2 different Systems and both the same problem. one with an NVidia GPU and the other with a Integrated Radeon (laptop). This is with a fresh Install of Win 7 64 bit Ultimate.

Check File's permissions for Houdini's Installation directories and my documents ,Be sure all of them are accessible by “Every One” ,Also run Houdini as Administrator :idea:

I had exactly same problem on Linux Mint ,But my problem solved when I set File's Security correctly ! :?