I may possibly have just killed both my main and my backup hard drive from recent months.

running USB hubs off USB power (i.e. without external power) with multiple things plugged in at once may be the culprit. Dunno why I did this again… two drives and a card reader are too much for one port??

yes.

the devices ought to power themselves down or something. I thought USB had more smarts built in about power draw... ??

You'd think so. It is 2013 for cryin' in the night. Although I am still waiting for my flying car...

thought i'd written that dethamus! weird L)

now see if any of my other hard disks have enough space on them to try to copy what I can from the less-hurting of the two drives.