Lost IDE Drive

I recently added a P4C800E Deluxe Motherboard
System will not reconize IDE drive
Sys.Config:
Asus P4C800E Deluxe (875)
1- 120gb IDE HD (Connected to Pri as Master)
1- 300GB ATA HD
DVD BURNER
DVD R/W
2GB DDR
6800 GS AGP Graphics

System will boot and recognize IDE drive after running it will reboot and flash Error Loading OS
Other times it will load OS and recognize drive,then will freeze after running for a time,after reboot message Error Loading OS

Drive not seen in CMOS Configuration

Cannot pin point problem,take system down and check the cables and everything is okay for a time,set system back up and the problem re-appears

Thanks Advance