Shortcut bar no longer allows opening mutiple instances of program

[Ray]

Before replacing my c: drive and reinstalling Office 97 pro, with Word
(or Access or Excel) already open once, I could click on the same
shortcut button again and open a second instance of the same program (so
I could do side-by-side comparisons of different versions of a document,
database, etc.). I can't any longer. I merely return to the instance
already open.

To get a second instance now, I must go to Start/Programs/Microsoft
Office/Microsoft Word (or Excel or Access).

Thanks for you help.