MYLEX RAID CONTROLLER

ALTOS 1100E server with MYLEX DAC1164 RAID CONTROLLER with 3*9.1GB U2W SCSI in RAID5 configuration. WINDOWS NT 4.0 with SP4. system is not coming up now. after the server is switched on raid info is o.k. but after the system info screen(PIII processor,memory etc) blank screen coming.we are not getting the nt selection menu and no error meassage. no abnormal shutdown yesterday. no problems in the last 6 months.today when switched on this problem.raid is o.k.

please help me. this is online server connecting to stock exchange.