Why is Date Changing

[Robert Boucher <boucher1@alumni.utexas.net>]

I keep a lot of information using AW 5.1 on a IIe. I use a Zip disk to
backup these files onto an iMac (9.2.2) and a Powerbook (8.6). Recently,
when trying to copy, I get a message a newer version of the file is
already on the Macs. On either Mac, the files on the Zip disk have dates
in the 1940's, i.e., July 19, 1948. When I catalog the Zip disk on the
IIe, the file dates are correct. All computers are showing the correct
time.

Any suggestions on what is happening to the dates?