I have determined that if I remove the Avg Time Spent metric in the report I no longer get the error. I assume it has something to do with Adobe changing how they calculate Avg Time Spent in their spring release. It is throwing that error in older reports.
I too had the same issue today where Adhoc Analysis would not launch. However, I have not switched computers or made any changes. I ended up having to close all browser windows and log back into SiteCatalyst for Adhoc to launch.