On Tue, 15 Mar 2005 15:02:12 -0500 Dan
wrote in Message id: :

[...]

Just now, I was using Zone alarm to virus scan a particular large
folder, & the clicking occurred perhaps 6 times in rapid succession.

As other have said, it looks as though your drive may be dying. I would
check your system event logs to see if the errors are severe enough to be
logged by the OS.