I am trying to do a very large recursive operation, but it just hangs up. IS there any way of pausing t for some time, then make it continue?

Thanks in advance.

This System.Threading.Thread.Sleep(100); makes your code to wait for 100 ms. But it doesn't yield CPU time to other threads if that's what you want. Use Application.DoEvents(); to yield some CPU time to other threads as well.

You may also use both together:

Application.DoEvents();
System.Threading.Thread.Sleep(100);

but I would try to avoid recursion in the first place and use BackgroundWorker if possible.

HTH

Every recursive operation has to have some kind of stopping condition.
If not, you can create a stack overflow or some other error.
Look at the classic example of the factorial calculation:

uint factorial(unint n) 
 {
     if (n <= 1) {
          return 1; // stopping condition
     } else {
          return n * factorial(n-1);
     }
 }