Vista 32 ASUS P5KC Mobo Intel Q6600 CPU Antec 650 W PSU Two SATA 320 GB internal drives connected to SATA slots 1 and 2 of 4 An external ASUS eSATA and USB2 enclosure with WD 640 GB SATA hard drive connected to an eSATA port on the computer. The external eSATA hard drive works fine after a reboot but after a few hours it vanishes and cannot be found by Explorer or the Control panel even though it has not been accessed to modify, delete or add files. A reboot finds the drive and it works again for a while. I have an eSATA backplate port connected to slot 3 on the mobo. The mobo also has an integral eSATA port on the back. The problem occurs when I connect the external drive to either of these ports. The external enclosure also has a USB2 connection - if I use this the problem does not occur indicating that the hard drive itself is OK. Any suggestions?