safely Remove Drive

[Mark]

I haven't seen anything on this issue lately, and it's driving me up
the wall.  As I posted recently, on the machine I am testing (Dell
Precision 5500, 8cores, 4GB RAM, tiny disk) with a fresh, updated
install of 10.10, when I right-click a USB drive icon and click the
"Safely Remove Drive" link it works, first time, just the way I'd
expect it to.

However, on my main desktop at home (hand-crafted, X4, 4GB RAM, disk
to spare, fully updated fresh install of 10.10), I have to do this
routine twice (right-click, select the "S-R-D" link) before it
releases the flash drive.

I dumped the entire gnome configuration on each machine and compared
them, and the differences are all what I'd expect to see - absolutely
nothing stands out as even related to this (and the ones that looked
mildly suspicious all turned out to be red herrings).

Could it have anything to do with the hardware itself?  The machines
are significantly different at that level, but except for the specific
variety of packages that are loaded onto each, the software is pretty
close.

Baffled.