My server is w2k and domain controller. I have problem server slow respond because cpu usage 100% when I open task manager lsass.exe usage .what is it ? How to fix this problem

Hi Uhu,
Hope this is of some help:

http://support.microsoft.com/kb/308356

Be aware that there is also a "Sasser" virus:

http://ask-leo.com/what_are_lsass_lsassexe_and_sasser_and_how_do_i_kn ow_if_im_infected_what_do_i_do_if_i_am.html