Irregular recognition

I have an ATA100 controller (Promise) on my motherboard (ASUSA7V) and have recently installed a maxtor 40GB HD (6LO40J2/not the primary drive). When I boot the computer, sometimes the controller (bios) recognizes this drive and sometimes it does not. When the controller does not recognize this drive, neither does Windows 98SE and this drive does not exist. I can immediately shut down the computer and restart and the controller sometimes recognizes it after the first restart, but not always.Any suggestions?