dealing with a slightly flaky USB drive; unkillable bash process

[Adam Funk]

Hi,

I have a USB hard drive with a luks + ext4 partition on it.  The drive
started acting flaky recently, so I bought a new one & am now trying
to copy the files off the old one.  It connects fine, with the
passphrase dialog, &c., but occasionally "drops off" a few minutes
later.  When this happens, the /dev/mapper/luks-<uuid> device doesn't
disappear, so I get an error message trying to remount the partition.
Then 'sudo cryptsetup luksClose luks-<uuid>' gives a bunch of error
messages about the device still being in use, & gives up.  

I've also noticed that I end up with a bash process (with no child
processes) running around 99% of CPU in 'top'.  This process can't be
killed, even with 'sudo kill -9 <pid>' --- I end up having to reboot
the laptop, sometimes having to do a hard shutdown (i.e., with the
power button).

I would appreciate any suggestions for getting the drive to work long
enough to copy the data off, & for dealing with the seeminly
unkillable bash.

Thanks,
Adam