Organizer is Messing Up My Dates

On my MAC, I have scanned a thousand paper photographs from family archives.  These are not from a digital camera, so no date information.  I have painstakingly edited the info on each photo, and manually changed the date to my best guess as to when it was taken.

Thinking of changing to Photoshop Organizer, so I exported, about 300 pix from the Mac, MAKING SURE TO INCLUDE Title, Keywords, Description and Location Information.

Import them into PS Organizer on a Windows PC.  Two problems:

     1.     On SOME pix (not all), the date was randomly changed!  Yes, I went back to the Mac to confirm the manual date entry I made was accurate.  For example, one pic had a date of 6/15/1988.  Once imported into PS Org, the date has been changed to 2/8/2011!

     2.     All of my location tags (again, manually entered for the paper scans) were ignored.

Why for pete's sake are just some pictures just changed to just some random date?   Who writes this software to produce such untested and unreliable results?