windows application blanks out

Question

I created a c# windows application that does a lot of probability calculating of random number drawing. If I use small numbers and a few intervals (probabilities of 1:3003 1000 intervals) it works fine, it contiually displays the changing calculations of numbers in the text boxes. If I use big numbers and large intervals(any larger than 1:3003 and 1000 intervals), the program works so hard that the windows application goes blank and appears frozen until it is complete and then it displays the final inteval results.