A few questions;

1. How are your "different" exposures set up?......Are they bracketted?  ie, +3.0Ev, +2.5, +2, +1.5, +1,+0.5, 0,  -0.5, -1, -1.5, -2, -2.5, -3.0Ev....I know that gives me 13 exp...but you know what I mean...
2. 12 RAW files into CS2 to create an HDR will require a lot of memory/horsepower...are you sure that's not the problem?( although your error message says otherwise)....Usually a 5 exposure bracket 2 up, 2 down and one even, will do just fine.

In youth, we learn....with age, we understand.