Possibilities:
Bad USB Port
Bad USB Cable
Bad Power supply for the drive
FWIW, Maxtor is a generally reliable brand.
Honu
Not to knock Maxtor, (they were recently taken over by Seagate so
hopefully their quality will improve) but I know of many people
including myself that have had terrible luck with their early models,
and I'm talking years ago, when external drives were first introduced.
The issue then was Maxtor external drives had extremely flimsy tiny
and I do mean tiny very fragile circuit boards inside the enclosure
which of course you weren't suppose to open that were not much bigger
than a postage stamp that the external power cord and the firewire
cable were connected to this. The problem was if you yanked the power
cable out of the drive several times, in about a month this cheesy
little circuit card could fail. I went through not one replacement,
but two in about six months time because at the time I was using this
so-called "portable" drive, (how it was marketed) not just an external
to lug it around with me. I finally opened the case, breaking the
warranty and saw what I described above.
Note to the wise, what's inside was just a plain IDE drive (may have
changed now) that had a cable similar to the end of a IDE cable that
just pushed on to this circuit card. After undoing the cable and
removing the drive it worked fine, in other words there was absolutely
nothing wrong with the drive itself, the problem was this piece of
crap circuit card that obviously was not designed well and couldn't
stand up to even gentle handling.
