ArcObject 9.3.1 VBA Compile Error: Automation Error

I have written a code in ArcObject 9.3.1 VBA. It works fine in my machine both Windows XP and 7 system. But another machine have just updated to Windows 7 and the MXD can not be oppened now. It shows 'Compile Error: Automation Error". And ends to the first line of the 'This Document'. Don't get a clue why? Here is the screenshot.

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