[TenTec] Orion II master resetting each turn on

[DieselCar at aol.com]

Hi All,
 
My Orion II have been running flawless since February 2006. But now after  
it has had a good nights rest and it is turned on the next day, the MASTER  
RESET COMPLETE appears in the bootup window.  Now I have to reset all my  
preferred  parameters. 
 
I believe that there is a lithium battery that holds its setting.  This 
maybe the culprit.
 
Has anyone else has had the problem.  And if it is the lithium battery  
then where is it located.
 
Please advise and thanking you in advance. 
 
73 de Rick W4UEF