I recently rebuilt my machine from an AMD X2 6400 (dual core 3.2 Ghz) with an 8800GT to an Intel Q9550 (Quad core 2.83 Ghz) with the 8800 GT. On the old AMD system, I was able to run Rosetta and GPUGRID at at the same time and have three total tasks running simultaeously; two for rosetta and the single GPUGrid task. On the new intel system, I can only run three rosetta tasks and the one GPRUGrid task simultaneously. Anyone know why rosetta can't take advantage of the last unused core?

You have not completeed any tasks so we cannot see the BOINC Version... which version?

If 6.4.5, did you update the configuration files?
If 6.5.0, are your use processors set to 100%?

Those are the first two things that come to mind ...