Y0 template rewritten/ATI5 returns ERROR

USR V92 external modem – in use for 2 months w/o an issue. Now, the Y0 was been, seemingly randomly, rewritten (not back to default). ATI5 command returns “ERROR”. This is the 2nd modem, on seperate systems, this has occured on. There were no changes made to the systems or modems while they where in use. Any thoughts on a cause?