In order for the caching mechanism for ScreenSteps to work you must modify the permissions on the ScreenStepsLiveCache Apex class included with ScreenSteps for Salesforce.
Setting permissions on the ScreenStepsLiveCache Apex class
Updated Feb 03, 2016
FYI guys, you can't edit Apex Class Security via the Action column in Apex Class list view in a production org. You have to open the class and then click Security. The method shown above is for sandbox.