I'm guessing you are asking about Forms 10. When logged in as an administrator, click on Processes. Once on the processes page you will see a blue "Instance Monitoring" at the top of the screen, click it. This will allow you to see all processes, In Progress, Suspended Tasks, and Terminated.

Select the status tab you want to see. From there you will see all of the instances with that current status. From there you can select the 3 dots at the end of the instances row and choose View Error Log. This will pull what is in the event viewer for you to see. Some items don't have anything, but you can click on the instance row and then see the different steps it took and figure out where it stopped. Some times this isn't very useful, but by knowing the step it suspended at you can look at the variables tab and see if maybe a variable value is missing that that step was reliant on. If it couldn't assign a task to someone, in the instancedetails you are able to select the 3 dots next to the corresponding step and reassign it to someone else.

I hope that helps.