I am running XP HE SP2 with Word, Excel 2002 SP3.

I have numerous Word documents as main documents and 1 Excel file as the
data document.  All files are stored on an external HD.  

At work, I am on a large domain running XP PE with Word, Excel 2000 or XP
(?).  I copied all of the files from the external HD to the HD on my work
computer.  The path to the Excel file is identical.  When I opened any of the
Word documents, they opened fine but the mail merge capability was lost (the
mail merge toolbar was greyed out).  All of the merge fields were in the
document and when I reset the Word file as mail merge and directed it to the
Excel file it worked flawlessly.

Why did I lose the mail merge capability after copying the file?  I am
hoping there is an easier solution than having to set each of the 40 Word
documents as mail merge individually.

Thanks in advance.  Any advice is greatly appreciated.