Hi there. I think what you need to do is click on the "help" tab (there are four tabs when you launch 3DMark11) and uncheck the "scan systeminfo" box. AFAIK this is a known issue with 3DMark11. After you have disabled the "scan systeminfo" function you will find that the benchmark runs fine
BTW post back and tell us your score! My 2500K@5Ghz and Radeon5850 Crossfire got me a score (on the normal test - "performance" I think it's called (the 720p one)) I scored 7137!