NULL hWnd returned from CreateWindowEx for class MWEDITTEXT1071185920 Error?

I have a program that performs a series of calculations for a large number of data sets. When I run it in a normal for loop it ones with no errors. But when I run it in spmd I get the following message

NULL hWnd returned from CreateWindowEx for class MWEDITTEXT1071185920

I was wondering what this message is and I might be able to stop it from appearing. It makes it hard to monitor how the program is progressing as it takes up most of the command window.