Lsass.exe I/O read/writes all the time ?!?!

Hi,

I have windows XP PRO SP3 and I recently found out that the lsass.exe process is doing I/O reads and writes all time. Another strange thing about it is that it does that at a constant speed, always reading and writing 3 bytes/second. I have another pc with windows xp and it doesn't have that issue, the process is almost always idle. I haven't set up that comp so i don't know how to fix that.
I know that the lsass process has variable functions, some critical, but others probably not. Maybe I can safely disable one or more of them. Can anyone tell me weither there are any functions related to lsass that i can disable without encountering any troubles and how I have to do that?

Thanks