Error during user switch (read).Message no. XMS_ADM100

Hello, Experts:

      we are using SNC system.    We have already had a client 600 in server SN2,  and now created a new client 700.

   in client 700 system ,  a XML Message came from PI  and occured  a errer for SNC side reason.    Once the error was corrected in SNC, we need restart the XML message. but while  carring out the restart button,  a logon window poped with Client 600 and user input.   the actually clinet is 700. So will appear error 'Error during user swithch(read)'.

   I guess a  across client setting  caused the error. but I don't how to do ?

thanks.

Jesse