We faced the same problem at the time of implementation...
The script was use full, so i have posted it in my download section... you have to run switchusermodetocompmodetool.bat once it will change user mode client to computer mode...
Mode change and group shifting problem of clients reduced after running it on all servers.....
REF:https://www-secure.symantec.com/connect/downloads/move-clients-groups-based-ip-and-switch-usermode-computer-mode