From D1 to D2 - Error reading symbol file

I have created several applications in  Delphi (1.02) and I now wish
to transfer some of them to Delphi 2.   I have copied all the various
*.DPR, *.PAS, *.OPT, *.DFM, *.DCU  etc ...  files from my Delphi 1
directories to the Delphi 2 directories but when I load up the
application I receive an error:  'Error reading Symbol file'.

The error does not appear to disturb the program in D2 and it runs
without any obvious problem.  Can anyone advise what the error is
actually referring to?

many thanks,