In Response To 'Re: Re: Variance freezes for certain sample sizes'
If the "reset" suggestion doesn't help then perhaps this might give some clue:
Enter each of these in separate cells with a <shift><enter> at the end of each.
Trace[data = RandomVariate[NormalDistribution, 5]]
Trace[data = RandomVariate[NormalDistribution, 10]]
Those are probably going to print out a lot of diagnostic information that you may not be able to wade through. But when you are finished with all four then either save the notebook where you can find it and attach it to your next message or just select all of it and paste it into your next message then perhaps someone can try to spot what the difference is between 5 and 10 elements and track down the cause of the problem.
If the diagnostic information is too big and you can't post it all then repeating the evaluation a second time will usually display a lot less information, but might still be enough to help track down the problem.