Hi this is not enough information for us to help.
What was the error message? Did you get any output DWI from SlicerDCM2nii? Did you use this output for anything?
What “new software” do you mean? What “image” were you viewing? (DWI? tensors?)
What do you mean by “distorted”? Spatially distorted? The wrong colors? Can you share a screenshot that does not contain any patient identifying information?