Lock Excel Document after a certain Date
How can I cripple an excel document after a certain date?  I want it to become unusable after, say, 12/31/2009.

I was thinking about putting one of those Must Enable Macros things in there that hides all the sheets on close and leaves one tab that says you must enable macros.  Then having an on open macro that unhides all those tabs, but also will close itself if after a certain date.  This has a few drawbacks in that someone could just enter in the macro code (without macros enabled) and change the expiration date... or even just change their system time.  Any thoughts about good ways to do it? Is my method pretty much as good as you can get? or are there better ways out there?

Thanks.
Lock Excel Document after a certain Date
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How can I cripple an excel document after a certain date?  I want it to become unusable after, say, 12/31/2009.

I was thinking about putting one of those Must Enable Macros things in there that hides all the sheets on close and leaves one tab that says you must enable macros.  Then having an on open macro that unhides all those tabs, but also will close itself if after a certain date.  This has a few drawbacks in that someone could just enter in the macro code (without macros enabled) and change the expiration date... or even just change their system time.  Any thoughts about good ways to do it? Is my method pretty much as good as you can get? or are there better ways out there?

Thanks.