Let the hive mind of Engadget get that for you.
"I commonly need to boot a system from an external disc and take a snapshot of the host system. I also then need to burn a copy of the image to a DVD. While I can do it with two separate external devices, and two power supplies, and two I/O cables, it'd be nice to find a small dual-drive enclosure. It would need to have USB, eSATA, and FireWire. Either slim-line or half-height bay for the optical burner would be fine, and space for either a 2.5- or 3.5-inch hard disc. Any ideas?"
Thanks for your tip. I measured with a Fluke TrueRMS series meter, if that helps. The laptop is not connected to the cable line at the moment so I can't try, but when one part of my body was grounded (for instance to my mix desk chassis) and I touched one of the laptop's screws or the serial port shield etc, there was a very prominant (but not painful) current flow. Very similar to those prank toy shockers. That gave me reason to believe there is a significant flaw somewhere. I will measure again with a resistor in series next time as you suggested and see what happens.