HELP PLEASE

[hass_2k]

hi
im faceing a very big probelm in my server TRU UNIX 64 ES 40 ELPHA SERVER... here is the story my sever was runing nicly and normally i got i massage saying the fan so and so faild i have shutdown the server i fix the new fans then i start up my server after cupels of hours my server start rebooting by it self and when i try to boot the server agine it wont after some time i shut down agine i return the old fans then i boot my server noramlly then it works but after cuples of hrs it reboot by it self could u plzz help me with this
thanking u
hass