I had a difficult time finding the solution to this problem, so I thought I would post about it to make it easier for the next person to find.
The problem is that when trying to select a destination space while setting up a simple workflow, a box appears and a graphic spins forever. Spaces never appear from which you can select.
The solution that worked for me was to edit this file: tomcat\webapps\alfresco\scripts\ajax\picker.js