Windows ent 2003 sever hangs

the PDC server hangs windows ent 2003 server sp2, there are not errors in the

event viewer.

it hangs once or twice a week , not at the same hour. it began doing it 5

month ago. Hardware seems ok. HP ML370 G4.

i see the explorer is hang because there are no taskbar, also nobody can

connect to the applications, the services are not working. The network is ok,

ping is responding. I have to shutdown the server pressing the power button.

any ideas where i can look for what is wrong?

tnx