Im running CS4 on windows XP. I was'nt getting any error message at all, it just sits there like it's busy. On a machine configuration note(I know this isnt the place for that) I have a 850 watt PSU, I7 3.0 processor, EVGA X58 confidential board, 3 gig of Corsair Terminator 1600 mhz ram, and two EVGA 9800 GTX cards running. I did notice when I started my machine up that the startup sound for XP was weird and the cursor movement would lag. So what I did was remove 1 video card to see if it was a power thing. It did stop the windows sound from being weird, but the extensions are still hanging. This machine isnt that old and I've had my extensions and CS4 running before it. I'm wondering if maybe I'm lacking power overall. But they did work before I formatted my machine. When I select my template in step 1 of Data Assist I get the hour glass for a moment, then it goes to step 2 and I get a pointed finger hand cursor that don't allow me to select anything in step 2. Once I try to it shows Data Assist not responding, even while waiting.