When running the AccuRev client, command line or GUI (acgui) on Windows 7 and 10 and you see the message ANOMALY: use of REX.w is meaningless (default operand size is 64), this is not an AccuRev related error message, but from the Windows OS.
From the command line the error will be reported in the terminal/cmd window. In the GUI you will see a pop-up dialog box.
A web search of " ANOMALY: use of REX.w is meaningless" provides lots of Win 7 and 10 hits. These Microsoft pages may help.
Check your Anti-Virus as this has been a problem in the past.
For more information contact AccuRev Support