restart problems win98se

i recently built a computer with the 748lmrt motherboard from pcchip, intel celeron 400mhz sepp processor, at power supply, 64 mb pc100. everytime i install something and it says to restart the computer, the computer reboots, but doesn’t come backto the windows desktop. it stops with a blank screen and cusor blinking. i have to turn the computer off and back on twice everytime to get it to start again. i’ve never used the AT power supply before. can someone help me? thanks ls2450@earthlink.net