I am importing data from a logging application
(as in data, not trees), and the first entry of each row
is a timestamp--as in the number of seconds since
the epoch, which is January 1, 1970 or something
like that. The problem is, I cannot see how to make
this a date in Excel. All of the standard date and time
options in "Format Cells" do not know how to convert
this--that is, it puts "#########" in the cells.

Any ideas?

Chuck.