When trying to open a report or even looking at a data source, SharePoint would throw an exception: "Report Server has encountered a SharePoint error. ---> Microsoft.SharePoint.SPException: The context has expired and can no longer be used. "
I tried the usual remedy steps such as IISRESET and rebooting the server. I then tried to repair the RS Add-In and even run the SharePoint Configuration Wizard. Nothing was working, but I did notice in the logs that the timestamps were not the right time.
After several other actions, I decided to fix the clock on the server to have the correct time. Wow ... This resolved the context issue and everything started working. The clock was so much different than any client machine that the security context was assumed to be expired.