System Process high CPU usage

Hi Team,

I have been working on win server 2003 it is a file server and found that "system" process taking high CPU usage for some particular time and gets normal and then again gain high CPU usage.

During CPU usage if i disable SEP then server becomes normal immediately.

please provide me with permanent solution and cause for it.

SEP: 12.1.4112.4156

SEPM:12.1.4104.4130

please let me no for more infomation.