XPS730 e-SATA issue

​First post so please be kind.​

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​First week with 730. Vista. No RAID. Turned on e-SATA controller. Connected it to my WD external hard drive. Connection successful. If copying one or two files works fine. If I copy 2 or 3 gb's worth of files or I do a full scan "C", "D" and "G" with Kaspersky Internet Security both get about 90% of the way through copy/scan then lock up and nothing happens. WD HD is fine with USB 2.0 - large files and scan of "G" drive (WD) works without a glitch. ​

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​Any ideas of why e-SATA fails on scan to external hard drive or large file transfers to my "C" drive?​

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​Other than this I'm happy with machine. Worst case is that I turn the controller off and continue to use the USB.​

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​Thank you.​