System error during lock operation. Execute diagnostics in SM12

hi ; good day

When i try to change the output device in SPAD for a printer setting it shows "'Error in lock management Continue in display mode "".

i tried SM12 then it shows the error

''System error during lock operation. Execute diagnostics in SM12''

i cannot execute diagnostics..it shows the same error...

4.5 B , Oracle ,Aix

thanks&regards

seethy