1. Motherboard drivers.
2. Power supply issues.
3. Bios out of date.
4. Incorrect cable type or jumpers.
Bob
My current setup is:
WD 250GB SATA as the primary (C)
Seagate 160GB ATA as the secondary (D)
Win XP
My computer will recoginize the D drive, but after a few hours, or after hibernation, it will dissapear and I have to reboot.
The cable connections appear to be good. How do I repair this?

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