Inaccessible Briefcase On WD External Drive In Vista Home Premium

I'm using a two-month old Dell Inspiron 1520 laptop running Vista Home
Premium 32-bit. My first laptop was a Dell Inspiron 5100. That lasted me from
mid-March 2004-October 2007. In mid-March 2007, my internal drive crashed. So
my dad bought me a new internal drive as well as a Western Digital external
drive. He took the old drive into work and recovered all of the files I would
have wanted recovered. He then put them on the external and then I copied
them over to the new internal. The new internal drive lasted until
late-October 2007, at which point my parents decided to get me the 1520. I
have a briefcase on my desktop that I copied over to my Western Digital drive
for backup purposes. A few days ago, while trying to synchronize the two
drives, I discovered that I could open the external drive from "my computer",
but when I tried to update the briefcase, it said it was inaccessible. So I
disconnected the external using the "Safely Remove Hardware" tool,
reconnected it and tried again, but the same thing happened. I'm able to
access other folders on the external. I really hope my external drive isn't
bad because I can't afford a new one.