Looks like both have different date system
Change them to follow the same date system by going into
TOOLs-OPtions-Calculation
and uncheck 1904 date system from both your Windows machines.
If using Mac I guess leave them checked

"rrjohnsonia" wrote in message
...
I often copy cell contents from one worksheet and post them into a new one.
When I copy one set of dates and paste them into a new worksheet, the date
falls back one day and to 2001. For example, an original date of May 30,
2005
copies as May 29, 2001.

Our agency's IT guru can't figure it out. I could use some help to end
this
frustrating error.

Thanks.