Error reading RMS Protected Messages in Outlook: System clock has been tampered with
A user had a problem trying to open email protected by rights management.
When he tried to open the RMS protected mails in Outlook, he kept receiving an error:
"System clock has been tampered on the machine. Reset it and try again later".
The clue here is the recommendation to "try again later" as this error will occur if the clock on the receiving machine is ahead of the sender's clock. As time passes and the clock on the recipient's computer passes the sent time, the message will open without error.
For more information on this and other RMS issues, see RMS FAQ: Administration